Long post because I'm a Sniper fanatic.
Overall:
MSG-90 > SR-25 Sandfire > SR-25 > L96A1 > L96A1 Ghillie/Arctic Wolf > M24 = M24 Woodland > Dragonuv SVD = Dragonuv Black
Accuracy:
M24 = M24 Woodland > MSG-90 = SR-25 = SR-25 Sandfire > Dragonuv SVD = Dragonuv Black > L96A1 = L96A1 Ghillie/Arctic Wolf
Fire Rate:
SR-25 Sandfire > SR-25 > MSG-90 = Dragonuv SVD = Dragonuv Black > M24 > L96A1 = L96A1 Ghillie/Arctic Wolf
Portability (pretty much useless aspect, better of switching to a knife if you need to run and then switch back):
M24 = M24 Woodland > MSG-90 = SR-25 Sandfire > SR-25 > Dragonuv SVD = Dragonuv Black = L96A1 = L96A1 Ghillie/Arctic Wolf
Recoil (most to least):
Dragonuv SVD = Dragonuv Black > L96A1 > L96A1 Ghillie/Arctic Wolf > M24 = M24 Woodland = SR-25 = SR-25 Sandfire > MSG-90
Though the L96A1 could arguably be placed higher than the SR-25 due to the shots required to kill with an SR-25 and its stealth deficiencies.
MSG-90 is the best sniper rifle in game. It is a semi-automatic sniper rifle with a 10 round magazine, with three extra clips. It does enough damage to consistently 2hko even with the 10% Damage Reduction from a Suppressor. In accuracy, it is only bested by an M24, and has matching accuracy of that of an SR-25. It shoots slower than an SR-25, but it has less recoil, the lowest of all Snipers. It has the ability to use any of the three Suppressors available, which, along with its superior damage, place it in higher placing than the SR-25 and its Sandfire variant. I'll explain this in more detail later.
SR-25 Sandfire has the fastest fire rate of any sniper rifle. It however suffers from a huge damage deficiancy, where it requires upwards of four body shots on Heavy Armoured units to kill. It however has great accuracy, the same as an MSG-90, which can supply easy headshots. During the last patch, it along with its original counterpart suffered from a delay bug where it would jam for half a second before the bullet would leave the muzzle after firing. This has been fixed.
SR-25 is not as good as the Sandfire variant. It has slightly less Firing Rate but improved Portability, which is meaningless. However, the Sandfire requires a Supply Case to acquire, which can be quite costly.
Both SR-25 variants suffer from the pre-installed S1 Suppressor, or some sort of Suppressor at the least. This gives it the distinct high pitched sound, which makes it a dead giveaway to its position and existence in general. With this, one cannot change the Suppressor.
L96A1 has the most damage of any Sniper Rifle. It will almost guarantee a kill if striking a target, with the exception of far placed shots that hit extremeties such as 100m+ on the hand or foot, or through walls. The major drawback of this gun is its long chambering time for its bolt action and its pathetic accuracy. For any shot over around 60 meters, placing the shot can be extremely difficult.
The Ghillie and Arctic Wolf variants are worse though because they are automatically fitted with an S1 Suppressor.
The M24 is the most accuracy Sniper Rifle in the game, being able to fare shots well over 100m with almost zero bullet deviation. I've been able to make ~200m head shots with this, though it is extremely difficult. Although it is the most accurate Sniper Rifle, it suffers from its poor damage, almost always requiring at least two shots to kill a target at full HP, and its long chambering time. Though not as long as the L96A1, even if you hit a target, you are not guaranteed that you will be able to kill them, leaving you vulnerable since your target knows someone is attacking them. The L96A1 allows you to kill a target immediately so the Bolt-Action drawback is less. In the most tactical game-play, the M24 will fare better, but that is most likely only on Snow Valley where shots over 100m can be placed, and there are sniping spots that require the utmost accuracy to hit. Otherwise, the pure stopping power of an L96A1 has the advantage. The M24 does approximately 80~90 damage on a shot, leaving the target with Red HP and a heartbeat. It almost never kills someone on the first shot unless its in the head.
The Dragonuv is the worst Sniper Rifle. Though it is also Semi-Automatic like the top rated on my list, it has several horrible draw backs, and the only reason I would use it is if I picked it off a corpse. It has less accuracy than any other rifle except the L96A1 variants. This isn't a very large issue since its accuracy is still fairly high, but when combined with its difficult scope crosshair and its enormous Recoil, it makes it placing multiple shots difficult. Its only advantage is the pure stopping power. It cannot be fitted with a Suppressor so everyone will know you are there firing something huge and missing.
Suppressors
The most important part for the Sniper Rifle.
S3>S2>S1 for Sniper Rifles.
S3 allows you to reduce your Muzzle Flash by 50%. The easiest way to find where a Sniper, or any other unit, for that matter is to find their Muzzle Flash. Muzzle Flashes come from the gun itself so the source must be nearby and can't get very far. It's a very effective method to see through fog. The SR-25 and Sandfire variant, as well as the Ghillie and Arctic Wolf version of the L96A1 cannot be fitted with this, thus their Muzzle Flash is very immediately noticeable, whereas the Recoil advantage that the L96A1 versions acquire is of no importance since the gun almost always requires a re-zero after firing.
S2 allows you to reduce your Tracer Bullet by 50%. I've never found this trait to be particularly useful as I always notice Muzzle Flash. Tracer Bullets rarely ever allow me to do anything other than stay away from a specific turn where I may be shot by going, but not many people prefire corners like that anyways. If someone is shooting at me, I'll hear their bullets scarring on the walls around me or their gunfire before I notice tracer bullets either way, and if they're shooting in front of me, they're either aiming at a person in front of me where I will notice or they're aiming at me where I will already know I'm being shot at as I previously stated.
S1 allows for reduced Recoil. Not particularly useful on an L96A1 or an M24, but it could help on an MSG-90. If you have the option though, choose an S2 for the Bolts and an S1 for the MSG-90.
You should always suppress your MSG-90. There's no reason not to. You'll almost never OHKO with it. It only takes two, occasionally three for Heavy Vests or poor hits. L96A1 I would recommend but people almost notice those all the time regardless. Some prefer to guarantee their damage, and others like the intimidation factor of the noise. M24, the bolt action sound is a giveaway either way, but I prefer S3ing it so people can't see my flash, as I would with any Sniper Rifle. I wouldn't recommend S3ing any other gun though since the tracer bullets from an Assault Rifle are easily noticeable either way. Might as well go with S1 to improve Accuracy from Recoil.
Thus, the MSG-90 comes out ontop of the SR-25 variants for having a better stealth component, and more damage. The sound it makes is less distinct, and can be mistaken for L96A1s, leading to the opponent to underestimate the accuracy. Its fast fire rate allows for multiple hits and kills faster than an L96A1 can bolt and fire, and its higher Accuracy Rating allows for easier target acquisition, zeroing, and hitting. Not to mention it reloads faster than the L96A1.
With obstructed shots, I can easily take more chances with an MSG-90 than an L96A1, where if you miss, you have to hide while you chamber another bullet. You also have much better success at hitting the target.
Extended Magazines
I would highly advise against using extended magazines excepted possibly a Fast Loader on a semi-automatic, or an Extended 2 on an M24. The increased reload time on an L96A1 is horrid and will most likely get you killed or cause you to lose your target.
tl;dr
MSG-90 + S3 Silencer + Standard Magazine.
Overall:
MSG-90 > SR-25 Sandfire > SR-25 > L96A1 > L96A1 Ghillie/Arctic Wolf > M24 = M24 Woodland > Dragonuv SVD = Dragonuv Black
Accuracy:
M24 = M24 Woodland > MSG-90 = SR-25 = SR-25 Sandfire > Dragonuv SVD = Dragonuv Black > L96A1 = L96A1 Ghillie/Arctic Wolf
Fire Rate:
SR-25 Sandfire > SR-25 > MSG-90 = Dragonuv SVD = Dragonuv Black > M24 > L96A1 = L96A1 Ghillie/Arctic Wolf
Portability (pretty much useless aspect, better of switching to a knife if you need to run and then switch back):
M24 = M24 Woodland > MSG-90 = SR-25 Sandfire > SR-25 > Dragonuv SVD = Dragonuv Black = L96A1 = L96A1 Ghillie/Arctic Wolf
Recoil (most to least):
Dragonuv SVD = Dragonuv Black > L96A1 > L96A1 Ghillie/Arctic Wolf > M24 = M24 Woodland = SR-25 = SR-25 Sandfire > MSG-90
Though the L96A1 could arguably be placed higher than the SR-25 due to the shots required to kill with an SR-25 and its stealth deficiencies.
MSG-90 is the best sniper rifle in game. It is a semi-automatic sniper rifle with a 10 round magazine, with three extra clips. It does enough damage to consistently 2hko even with the 10% Damage Reduction from a Suppressor. In accuracy, it is only bested by an M24, and has matching accuracy of that of an SR-25. It shoots slower than an SR-25, but it has less recoil, the lowest of all Snipers. It has the ability to use any of the three Suppressors available, which, along with its superior damage, place it in higher placing than the SR-25 and its Sandfire variant. I'll explain this in more detail later.
SR-25 Sandfire has the fastest fire rate of any sniper rifle. It however suffers from a huge damage deficiancy, where it requires upwards of four body shots on Heavy Armoured units to kill. It however has great accuracy, the same as an MSG-90, which can supply easy headshots. During the last patch, it along with its original counterpart suffered from a delay bug where it would jam for half a second before the bullet would leave the muzzle after firing. This has been fixed.
SR-25 is not as good as the Sandfire variant. It has slightly less Firing Rate but improved Portability, which is meaningless. However, the Sandfire requires a Supply Case to acquire, which can be quite costly.
Both SR-25 variants suffer from the pre-installed S1 Suppressor, or some sort of Suppressor at the least. This gives it the distinct high pitched sound, which makes it a dead giveaway to its position and existence in general. With this, one cannot change the Suppressor.
L96A1 has the most damage of any Sniper Rifle. It will almost guarantee a kill if striking a target, with the exception of far placed shots that hit extremeties such as 100m+ on the hand or foot, or through walls. The major drawback of this gun is its long chambering time for its bolt action and its pathetic accuracy. For any shot over around 60 meters, placing the shot can be extremely difficult.
The Ghillie and Arctic Wolf variants are worse though because they are automatically fitted with an S1 Suppressor.
The M24 is the most accuracy Sniper Rifle in the game, being able to fare shots well over 100m with almost zero bullet deviation. I've been able to make ~200m head shots with this, though it is extremely difficult. Although it is the most accurate Sniper Rifle, it suffers from its poor damage, almost always requiring at least two shots to kill a target at full HP, and its long chambering time. Though not as long as the L96A1, even if you hit a target, you are not guaranteed that you will be able to kill them, leaving you vulnerable since your target knows someone is attacking them. The L96A1 allows you to kill a target immediately so the Bolt-Action drawback is less. In the most tactical game-play, the M24 will fare better, but that is most likely only on Snow Valley where shots over 100m can be placed, and there are sniping spots that require the utmost accuracy to hit. Otherwise, the pure stopping power of an L96A1 has the advantage. The M24 does approximately 80~90 damage on a shot, leaving the target with Red HP and a heartbeat. It almost never kills someone on the first shot unless its in the head.
The Dragonuv is the worst Sniper Rifle. Though it is also Semi-Automatic like the top rated on my list, it has several horrible draw backs, and the only reason I would use it is if I picked it off a corpse. It has less accuracy than any other rifle except the L96A1 variants. This isn't a very large issue since its accuracy is still fairly high, but when combined with its difficult scope crosshair and its enormous Recoil, it makes it placing multiple shots difficult. Its only advantage is the pure stopping power. It cannot be fitted with a Suppressor so everyone will know you are there firing something huge and missing.
Suppressors
The most important part for the Sniper Rifle.
S3>S2>S1 for Sniper Rifles.
S3 allows you to reduce your Muzzle Flash by 50%. The easiest way to find where a Sniper, or any other unit, for that matter is to find their Muzzle Flash. Muzzle Flashes come from the gun itself so the source must be nearby and can't get very far. It's a very effective method to see through fog. The SR-25 and Sandfire variant, as well as the Ghillie and Arctic Wolf version of the L96A1 cannot be fitted with this, thus their Muzzle Flash is very immediately noticeable, whereas the Recoil advantage that the L96A1 versions acquire is of no importance since the gun almost always requires a re-zero after firing.
S2 allows you to reduce your Tracer Bullet by 50%. I've never found this trait to be particularly useful as I always notice Muzzle Flash. Tracer Bullets rarely ever allow me to do anything other than stay away from a specific turn where I may be shot by going, but not many people prefire corners like that anyways. If someone is shooting at me, I'll hear their bullets scarring on the walls around me or their gunfire before I notice tracer bullets either way, and if they're shooting in front of me, they're either aiming at a person in front of me where I will notice or they're aiming at me where I will already know I'm being shot at as I previously stated.
S1 allows for reduced Recoil. Not particularly useful on an L96A1 or an M24, but it could help on an MSG-90. If you have the option though, choose an S2 for the Bolts and an S1 for the MSG-90.
You should always suppress your MSG-90. There's no reason not to. You'll almost never OHKO with it. It only takes two, occasionally three for Heavy Vests or poor hits. L96A1 I would recommend but people almost notice those all the time regardless. Some prefer to guarantee their damage, and others like the intimidation factor of the noise. M24, the bolt action sound is a giveaway either way, but I prefer S3ing it so people can't see my flash, as I would with any Sniper Rifle. I wouldn't recommend S3ing any other gun though since the tracer bullets from an Assault Rifle are easily noticeable either way. Might as well go with S1 to improve Accuracy from Recoil.
Thus, the MSG-90 comes out ontop of the SR-25 variants for having a better stealth component, and more damage. The sound it makes is less distinct, and can be mistaken for L96A1s, leading to the opponent to underestimate the accuracy. Its fast fire rate allows for multiple hits and kills faster than an L96A1 can bolt and fire, and its higher Accuracy Rating allows for easier target acquisition, zeroing, and hitting. Not to mention it reloads faster than the L96A1.
With obstructed shots, I can easily take more chances with an MSG-90 than an L96A1, where if you miss, you have to hide while you chamber another bullet. You also have much better success at hitting the target.
Extended Magazines
I would highly advise against using extended magazines excepted possibly a Fast Loader on a semi-automatic, or an Extended 2 on an M24. The increased reload time on an L96A1 is horrid and will most likely get you killed or cause you to lose your target.
tl;dr
MSG-90 + S3 Silencer + Standard Magazine.