It's all about the quake.

Most of the games on the list are running with the quake engine, including SOF2

quake
quake quake
quake quake quake
quake quake quake quake (comming soon

SOF2 uses a heavily modified version of the Quake 3 engine, not quake. I liked Quake 2 better than either other iteration though so Quake 4 sounds good.
EDIT- JSYK the various quake engines are very different and not the same so SOF2 isn't built on the Quake 1 or 2 engine, plus Quake 4 will use the DOOM 3 engine. Oh, so much Carmack Goodness

Probably been said before but "Best FPS title to date" doesn't specify platform, so my vote goes in under "other"

Halo baby.  I've never had any FPS game's single player hold my attention so well. (not to mention the obvious MP lovin')

Those facehuggers used to scare me half to death.  Especially when playing as the predator with your vision on thermal (hunting humans) and you couldn't see the little buggers before they were in your face.

Now, is it relating to single player, multi, or a general round up of both??

Some games the multiplayer kicks as$ where the single is quite poor.... and vise versa

There will always be something better, until something better comes along