I used to love Twitter, now I am all about my Facebook..I use both daily, I like, I hate to say, some of the FB games! Farmville and Cafeworld and like going to check out my FB friends diners and farms...yes, I know, I'm a nerd! LOL. We had a wine night on Twitter with the Twitter moms a few months back that was a blast though, hope we have another soon!
I can't really pick one or the other. I like Facebook because many of my real life friends use it, and it's a full website. I like Twitter because it can instantly improve your website's page views. If I had to give up one or the other, I'm not sure which one I'd choose!