Best classes ATM? From a BG perspective:
Ret doesn't do OMGWTF damage outside of CDs, but they're all but impossible to kill thanks to retarded self healing.
Mages are still bullshit.
Haven't seen enough Monks running around at 90 to form an opinion.
Spriests, Locks, Shammys And Hunters aren't so bad. (Well, from the perspective of a Rogue.)
Frost DKs are irritating as fuck.
Druids are pushovers.
Healers are crazy, but easily blown up inside a Kidney.
The best, IMHO: Warriors. I've been able to hold my own against every other class, to the point where it's basically "how good is the other guy?". The lone exception has been Warriors. Consistently rape my face off, despite Nerve Strike + Prey on the Weak. Only way I've managed to win these fights is by popping all CDs. (Shadow Blades + Vendetta + Trinket)