Single-player for me, my internet doesn't work too great for gaming. But like Uncharted, really really great game.

I like both, but Multiplayer slightly wins.
My Reason: Replay Value.

Single-player.

Completly off-topic:

I love your new av PDF

I voted for Singleplayer.

Most of my favorite game genres (RPG, sRPG..etc) don't lend themselves well to multiplayer. 

Multi-player is better it is more of a challenge beating a human opponent as opposed to beating a single player game even on the highest difficult level. Multi-player provides a high replay value and is highly addictive. Its more fun playing campaigns co-operatively than playing alone. Some single player games only are fun but the experience does not last long.

online with a great community.

personally, i cant sit there and play campign on like cod4 or uncharted for days or months. i usually beat the game on easy legendary heroic hard w.e then i play online after that. ill only go back and play campign or single player when im bored.

games like cod4 taht have offline arcade mode gives you a good reason to play again.

thats why i dont buy single player games like uncharted ratchet and clank, mass effect, dmc4, etc. i rent them or ill rent them and burn them for my ps2 , or get em for 10 bucks on my ps2.

when i look back at when i had my ps1 and ps2, i cant beleive taht i used to play those games so much without any online or multiplayer. i.e crash bandicoot, spyro, call of duty. i used to go play halo one capign at my firends house every weekend and love it. ive had my ps2 for 6 years and i never played online once, but i used to play single player games all the time. or maybe its cause the game was 10 bucks burned and i didnt really care.

although there are games like cricket 07 fifa 08 nba 08 that i dont care for online play, and manager mode keeps me occupied for months. i.e fifa 06, im on my last year finally with Ajax.

now i think online or multiplayer support is very imporant for gamers, thats just my opinion.

thnak god you can play 4 play multiplayer in cod4, ive been begging them for that since cod1.

Shoot man, that's too hard to decide. Sure, I like playing Counter-Strike, Battlefield 2, TF2, ect but I also like playing my share of singleplayer games. I guess it all depends on what you're in the mood for.

Single player.

Strategy games are the only ones in which I enjoy a good multiplayer experience. When it comes to FPS, I love a good offline match with friends and bots as much if not more than I do an online match. But in the end, single player is the most important aspect for me, in any genre other than strategy. And fighting games, but offline multiplayer is more important for me then as well.

And I agree about the avatar, PDF. It's great. I wonder what would've happened to Crash and Spyro had the IPs not been bought by Universal. The games would still kick ass, and Sony would have two mascots almost as notable as Mario and Sonic.