I will go with: Facebook
But, I don't use (Facebook / Twitter). I don't even use Facebook. I prefer to use MySpace, that's my favorite social-networking website.
Hmm, this is a hard one. i like 'em both, a lot. I wanna say Twitter, but on facebook, more of my close personal friends are on Facebook. So, I guess i am gonna go with facebook, in the end. But, not by much!
for me, are pretty useless. for someone who needs to broadcast a lot of information frequently (like some celebrity or politician) is just perfect.
:2 cents:
Definitely twitter! I find I can chat with more people faster on twitter, facebook is so slow in comparison. I've found lots of interesting people to follow on twitter