alot of people are not sure which way is up in hp, so I made a list and these are basically the only competitive classes:
Black Knight : Insane solo skills, does a lot of damage, no other class comes close.
Supreme dark lord: Best class for farming, i use it all the time, maybe a little more damage than bk
Keyblade Master: Hits like a truck, only class I know of to 1hk doomdungeon without potion or extra weapon.
Evolved Dark Lord: Good all-round class, a little better than udl as it is less glass cannon.
Ultimate dark lord: Decent offensive ability, not much else
DreadFiend: More of a transition class from lich and other low leveled classes to a good class, + easy to get.
Legendary DreadFiend: Gimped version of DF, takes forever to get (2% chance of 3 tokens) not recommended, this was good when there wasn't trading
Bard: Multiplies damage by 10, nuff said.
Chrono Breaker: Weak class but "kill time" amplifies a bk/kbm
Rogue Knight: Easy to get, kinda "meh" but has a forever stun (3 second cooldown 3 second last), which makes it a great support, making any boss killable.