ok, i know this is probably what you didn't want, but since this IS a gear mod game, you CAN make any class combo work...but other than that, it really depends on what you are looking to do with your char(e.g. tanking, pvp) is what will determine your class
so far:
mages - good in pvp, ok dps
knight - tank all the way, hard to play in pvp
druid - great healers, good in pvp
priest - good healers, great in pvp
warden - tank with a little more dps than knight, don't know about pvp
scout - ok dps, great in pvp
rogue - good burst dps, very much played as in pvp due to the burst damage and hide
warrior - great dps, good in pvp
those are just my thoughts, but some1 may be able to give you a better summery