I guess I'm a little bit of both, but I like playing social games. I play many solo games, but there's something about multiplayer games that I don't get with single player experiences; especially nowadays. I love online multiplayer because it allows me to play with way more people than local. The best local multiplayer can have is four players, but online can have twelve, twenty four, or even thirty two. Human players are a much different experience than artificial intelligence. I get more of a thrill knowing that enemy I beat was controlled by a person instead of a machine. I admit it's weird playing with total strangers, but with a headset we can at least communicate. People tend to cooperate better if they can talk to each other. Even without a headset, I still manage to use teamwork with players on my side, mostly through common courtesy. However, if I can, I'll play local multiplayer with friends because it's a fun way to spend time and bond.
I know there's downsides to online multiplayer, such as trolls, griefers, or people swearing, but for me, the good outweighs the bad. I treat my fellow teammates with respect and they usually do the same to me. If they're hurt, I'll heal them. If they're in trouble, I'll come to their rescue. I'm such a teamplayer, I tend to get friend requests from other players. I turn them down because I prefer to be friends with someone I can meet face-to-face.
I also notice that when playing with friends, we tend to screw up more often than we do solo, but we generally don't care. I don't care about beating the game, I care about having fun. Sometimes screwing up and losing is fun. My favorite games to play with others locally are Rayman Legends, 'Splosion Man, most racing games (like Blur), most sports games (like NBA Jam), and certain fighting games (like Def Jam: Fight for New York and Injustice: Gods Among Us).
Currently, I'm situationally a solo gamer because my parents won't allow me to keep the Xbox 360 and the public Xbox 360 on campus has been taken by the higher ups last month. Fortunately I have ShadowGun: Deadzone on my iPad and it allows me to get my multiplayer shooter fix. Once I get my Xbox 360 back, you can bet I'll be playing online. It's been a while since I played Halo 4, Blur, and other games with online multiplayer.
EDIT: Jeez, I must be the only person on Toonzone who likes playing with others. That one vote for social gamer in the poll? That's me. I guess growing up with a brother and having friends that are into video games steered me towards team playing.