Personally i play pvp as a shammy
Well if you are playing solo, no pvp or 1on1 pvp all classes are good, but thats what i think of the following:
Rogues: what i noticed is that, if you want to be sneaky and easy HK's .. become a rogue, you can camp at good contested quest locations and ahhhh
->Weak armor, but can do good starting damage - good 1vs1 - sneaks - if you get skilled on how to play, you can beat warriors or any race without much effort (ofcourse your cooldown on things is a killer sometimes)
Dont be a lock (No locks are good - i got so many in my friends list - they help me summon

) but they are the weakest atm, well for me i think
->Summoner's ... also free Healthstones and sexy minion
Shamman are very good,
They do have a bad side, in group pvp raids, they are totem droppers
->powerful if you know how to play, excellent in 1on1, use totems, secondary healers, also can rez people and themselves
Warriors - best armor - can stand and keep hittin and hittin ,, and hittin .. and than i earth shock for the last time and than quickly type /spit
->TANKS , can wear best armor (Plate /cry)
Priests - Good healers, primary job heal, secondarly ummm heal more,
Most passive players.... just have to stand back and stare and party hitpoints
-> Healers
Druids - never played one, but they are overall good match for me atleast, (i.e. only if they know how to play)
Paladins - never played one, but their shield is annoying, oh wait another annoying thing is their ability to heal completely using all mana yes even if have like 20 mana
Mage - What can i say , slowfall, portals, free food , free water, i always carry one is my grp, AOE AOE AOE, (area of effect spells that is)
Damn have to go to class, if you need some more questions answered , msg me or somethin
