Mostly this game. My computer disagrees with the graphical downgrade patch for TF2 these days, so I can't play that anymore.
I've grown quite fond of minecraft pvp though. It's ridiculously simple, but being able to build your own environments and lead sieges onto castles or towns is pretty awesome. It's a shame my usual group is starting to not care anymore.
My favorite PVP is in Battlestar Galactica Online. Truly epic fleet battles with tons of ships, small hit and run operations, dozens of systems, 1v1 Arena competition, etc. Excellent PVP, but low on content.