I hear a lot of people saying go to Drakes when you hit 51, and for some other classes this might be the case, but I just tested %/hr between Drakes and CDs in Kerning Square at level 51:
On my crossbowman,
Drakes: 251%/hr, I 1HKO about 30% of the time.
CDs: 346%/hr, I 1HKO all the time.
Small contribution, but I think it might be useful to know. CD maps can be hard to find though.
Here's how I leveled so far:
1-10: Maple Island
11-15: Power B. Fore quests.
16-18: Blue Ribbon Pigs
18-19: Hat quest (should get you to 19 and 99%)
20-25: Ligators (can stay at Blue Ribbon Pigs)
26-30: Mixed Stone Golem Mini Dungeon
Advance
31-35: Mushroom Kingdom Quests
35-50: CPQ Rombot Grind
-OR-
35-42: Ratz
42-50: CDs
Now, I'm only at level 52, so the rest is based of leveling other chars:
51-55: CDs or Drakes
55-57: Toy Trojans (can probably stay at CDs)
58-60: Dark Drake Mini Dungeon
61-64: Robos/Master Robos
65-70: Guard Robots (Eldestine) or Twisted Jesters
Advance
71-85: Twised Jesters
-OR-
Follow DarkManiak's advice above. I also recommend training at Big Spiders (Eldestine) in your early 70s.
On my crossbowman,
Drakes: 251%/hr, I 1HKO about 30% of the time.
CDs: 346%/hr, I 1HKO all the time.
Small contribution, but I think it might be useful to know. CD maps can be hard to find though.
Here's how I leveled so far:
1-10: Maple Island
11-15: Power B. Fore quests.
16-18: Blue Ribbon Pigs
18-19: Hat quest (should get you to 19 and 99%)
20-25: Ligators (can stay at Blue Ribbon Pigs)
26-30: Mixed Stone Golem Mini Dungeon
Advance
31-35: Mushroom Kingdom Quests
35-50: CPQ Rombot Grind
-OR-
35-42: Ratz
42-50: CDs
Now, I'm only at level 52, so the rest is based of leveling other chars:
51-55: CDs or Drakes
55-57: Toy Trojans (can probably stay at CDs)
58-60: Dark Drake Mini Dungeon
61-64: Robos/Master Robos
65-70: Guard Robots (Eldestine) or Twisted Jesters
Advance
71-85: Twised Jesters
-OR-
Follow DarkManiak's advice above. I also recommend training at Big Spiders (Eldestine) in your early 70s.