My DK is going to be strong in the next patch? Cool, I really play it for the solo ability and the fact that Warcraft 3 is one of the games I would credit with creating my love for gaming, and there is a tie between DK and Paladin to that game (the two classes I play most). The main thing I have learned from Mists though is try to pick a main and stick with it. I played lots of classes through WotLK and Cata. In MoP you are hit fairly hard for trying to change classes.
Closing the thread, we can't have everyone posting the same question and getting the same answer every hour. If you want to reroll just to be OP, just look at the forum posts for what people are crying about the most and pick one of those, any will work for your needs - or you could learn a class you like, and succeed / fail on your own merits: not 'the new broken'.