I used to love facebook. Now, it has almost turned into MySpace with all the applications, super annoying graphics, fan pages, brands, etc. Plus, I enjoyed it more when only college students were able to get accounts. Now, I get requests from colleagues, friends' parents and even random people who I've never met.
I still use facebook, but only through my Blackberry. I log onto facebook online maybe once a month! It's more simplistic on my phone and to me, the Blackberry version is pretty close to the old, original facebook that lots of people miss! In this case, less is more. :)
So, I'd have to say my favorite site is still facebook, but only through my Blackberry.