Warriors are hands down the best class right now. This is from a pure Arena perspective, and most if not all of the top rated players agree on this.
I think battleground balance is a myth. There are too many debuffs and buffs to accurately determine if X class is the best. You will often see insane numbers, but that is with the best buffs and debuffs assisting. If anything BM Hunters are the best for battlegrounds, I guess. Any ranged class would be great though.