I cant figure out which class i should buy I already have Blademaster Troll Spellsmith Pyromacer Evolved Shaman Shaman Mindbreaker and Darkblood StormKing What other OP class should I buy and why

Frankly, you don't need any more. I myself have the Dragonlord, Defender, Beta Beserker, Guardian and the Classes that require a membership on their other games such as Dragonfable and Mechquest. For an OP class you could try both Paladin or Necromancer as they are pretty good. My personal favourite is my Beta Beserker though which I got for being in the Beta test it's now unattainable.