Aran is the best designed class in maplestory, and here is why.

I never had an issue with skill placements.

When I'm using Demon Lash (or any of the 'hold down skill button' skills) or in the middle of a regular attack sequence, no other key on the keyboard works. For example, Attack Attack E Attack Attack = regular 4 sequence attack, does not open equip inventory.

Whereas on Aran, as long as you hit the keys in time, you can for example turn around between double and triple swing. Or take a small step forward between each attack, by timing things carefully (potions delay attacks = free time to move)

Demon Slayer mostly just actively discourages doing anything quickly and it's kinda frustrating.