Rogues pretty fun if you gear one out and get good with it. Rogue has always been my fav world PVP class simply because when things arent going your way...*POOF*..Time to recoup, follow the person and wait for a better time.
DKs are pretty fun. As frost nice burst and great aoe and as blood you are almost unkillable while still doing decent damage. Death Grip is just way to much fun when people think they are going to escape.