Come on. BFG was the bomb! Maybe it is just nostalgia, but I have much fonder memories of deathmatches back in those days than anything recent.
Honestly, I think the opinions are going to based on what you play a FPS for. For me, some games are just much more suited for their multiplayer than their singleplayer. Doom 3 for instance, I played the single player and loved it, tried the MP once or twice and thought it sucked. It was the same with the first Halflife (granted later mods came out that would change this). But like say COD4 - I never touched the single player and only played the multiplayer, because that's what I got it for.
If we break it down on a multiplayer only level:
Doom II: The first I played it was what it was...many many many hours just 1v1 occasionally we'd even get 4 ppl!
Hexen/Heretic: Couldn't get into them (can't even remember if these were mp)
Quake: Loved it.
*Team Fortress - I realized I loved that type of thing, more to come)
Duke Nukem 3D: Didn't find this as fun as Quake
Quake 2: Hated it. With a passion
Unreal Tournament: Didn't play
Unreal Tournament 2: Loved it
*Tactical Ops - Loved it
HalfLife (multi) - Hated it - I did like CS when I actually got around to trying it
Quake 3 - Was better than Q2 but still liked UT2/3 better
Halflife 2 (multi) - Hated it
*TF2 - Hate it with a passion. This is not TF..I'm sorry to the fanboys.
COD4 - I played alot of it, I considered this good, but nearly as addicting as I remember the old ones being
(in here I was playing Eve, overseas, and on the road alot, so not alot of FPS..I think I played BF 1942, but for all you could do, it just seemed pointless and no teamwork for something that was supposed to be team based).
BCBC2 - Trying it, but same as BF1942
I know I probably missed some there, but those are the ones that stand out in my mind. My guess though is that everyone's opinion of the list above will vary to some degree depending on tastes. That is my overall point.
Maybe I'm just getting old. I can feel the arthritis kicking in when I twitch to fire