What fps has the best online multiplayer

The FPS considered to have the best online multiplayer by many critics is Call of Duty. It has many different game modes like HeadQuarters, Domination, Team Deathmatch, Free-For-All. Also, it is more organized and the stats are fun to compare with other people.
If you are looking for FPS with great campaign modes Fallout 3 is a good option. Halo also has a good campaign but that is only for Xbox 360.