In World of Warcraft is it better to be a mage or a warlock for pvp mainly and what spec

People always say it - and I know it's annoying, but true - but it depends entirely on the player. Someone who likes a particular character will be very good at it; on the other hand, taking on an allegedly "awesome" class won't help you unless you really enjoy the character and its traits.

BUT... I suppose, on the whole, a good warlock gives me more trouble than a good mage in PVP. A lot of people will disagree with me, as mages are considered one of the best DPS casters. However, on both my rogue and shadow priest, I find very good warlocks can close to one-shot me. (Others are morons who just fear you constantly and are easy to kill, but the good ones are GOOD). A destruction warlock is the best spec; arcane/frost mages are also good.

In any case, be prepared to be the focus of an immediate "take down the clothie!" mentality from the opposite faction.