Quakeworld is unsurpassed in terms of the 'your favourites' category. The perfect blend of speed, skill and teamplay. I can appreciate that many people have moved on from traditional deathmatch now, but the tactical complexity in modern QW is boggling and as far as I'm concerned it is the ultimate 'competitive' FPS.
With the modern client and server updates, it is also arguably the most technically advanced FPS on the market (graphics engine aside). This may surprise many people, I can hear you thinking "sh'yeah right, an 11 year old game that's more advanced than BF2, Source, Quake4 etc" but how about this for a list of features:
-Completely customisable HUD (ALL elements, heck, it's even mouse-driven letting you place icons exactly where you want them)
-Multiview demo support (all povs recorded, splitscreen playback if desired)
-Advanced teamoverlay / map etc for demo playback
-Live streaming support (double click a url and you are there watching the game from any pov with full overlays, stats etc)
-Totally customisable gfx, crosshairs, console, hud, sound, teamplay options, auto recording/naming of demos/screenshots.... my cfg is over 100k in size!
-Fantastic netcode including clientside prediction and qizmo re-routing (ping 70ms to a Danish server? No problem, re-route via a different ISP and get 40ms!)
-Built in demo browser / mp3 player / server browser etc
-Advanced scripting (IF/THEN/ELSE)
-Native Windows/Linux/Mac/FreeBSD clients
-Great serverside mods for competition play (also pickup games)
-Advanced movie-making features (record directly to xvid+mp3, re-camming etc)
-Built in support for XML help files
...plus hundreds more.
Of course, it's the gameplay which makes QW great (otherwise it wouldn't have lasted this long), but as far as I can see it is now the perfect platform for competitive play too.