I really enjoy the PvP aspect of the game including BG's. What is the best class/race/spec for this?

The most OP class from a pvp point of view would have to be the ret paladin. The only class you'll have trouble with are warlocks. Against any other class you'll be fine to go answer the phone mid-fight and find yourself still alive and surrounded by corpses when you come back;P
Be warned though, that since the paladin class comes already pre-twinked, if you decide to twink a paladin, you will be considered to be gay by every single person that sees you;)

Never had a problem with a ret pally at 80
80 Frost Mage

Never had a problem with a ret palli as an elemental or resto shammie.  Nice buffs, I'll remove them.  Bubble and heal, I'll heal to, lets start this fight again. x3

You'll have a very hard time against DK's in the 50-59 bg's...

Because people care about 50-59 PvP

[quote]
Because people care about 50-59 PvP[/quote]

hahaha good point