the PVP spriest these days are pretty amazing actually. Even as someone who has just enough gear to get by in the wild can defeat 90% of the classes thrown at me.
I have trouble with DKs and Rogues are almost always hopeless.
Everyone else though, I have a counter to. I can silence casters, dispell their buffs and debuffs, I can avoid a warlocks fear, and dispell their immunities to my spells. Paladins are easy to kill because most of them rely to much on their bubble, which I just dispell.
Glyph of Dispell is nuts for PVP as well... almost to the point where when i'm up against a frost mage, and I see I have 3 magic debuffs on me, I almost am happy.