I start off at the Vista Forums, simply because I know more about Vista than 7. I come here, over to 8 once in a while, and some other forums just to basically read about things(like at BBR). Some music forums, sports, one for my fav "adult "model", and one for Android.
That's about it for forums. If you asked me this 5 or 6 years ago, the list would be tripled, but I got out of some things and ain't going back(World of Warcraft).