Heyyo,
I'd say F.E.A.R. is better. Quake 4 had pretty good SP, but MP for me is a downgrade. I mean, Q3A has one of the smartest MP bots of all time... how can Quake 4 be an upgrade when it has none? I mean, the least Raven could've done was port the Q3A bot to Q4 like valve at least did for CSCZ and CSS... and the official CS bot sucks compared to the Q3A bot, especially the revamped Q3TA bot.
Now, FEAR also lacks a MP bot.. which's ghey cause it has a pretty smart SP bot, then again that bot was built for campaign realisim and not a huge fragfest. To me FPS have been de-evolving a bit.. gameplay is sacrificed for graphics, coop is now a rarity, and MP bots are optional on the verge of rarity. Just great. Anywho, FEAR's MP is pretty fun, feels a lot like the campaign cause the graphics are still fancy as heck, and everyone dies after a few bullet hits, so encounters usually are over after 1-6 seconds. I havn't played CTF, but I'm sure you'll definately have to work as a team if you don't wanna die all the time trying to get the flag solo.
Btw, I found Serious Sam 2 better than Quake 4.. yet again though, gameplay sacrificed for graphics as the campaign's very good but short, and the netcode's worse than SS1's netcode (actually, it's hideous compared to SS1), and now SS2 only has coop, there's no deathmatch it seems. I guess the budget was spent polishing the campaign and the engine, but overlooked some parts...