Halo 3 is fine and all but nothing tops Halo: Combat Evolved PC's multiplayer. That game still has an active community and it's been going for about 9 or 10 years now. Can't say the same for Halo 2 Vista, unfortunately. Only 2 or so months until those servers shut down.
Currently playing MGS2 (360) and Super Mario 3D Land (2DS)