DMed: Three Homebrews, Greyhawk, Ravenloft, and Planescape
Played in: Two Homebrews, Forgotten Realms, Planescape
Not a whole lot of settings. For a long time I was anti-published settings, and I always ran homebrews. Then, I started playing Planescape, had one campaign in Ravenloft, and continued on with Planescape. Really, PS has covered a lot, though, including a campaign in Ysgard, Carceri, Outlands, two in Sigil, and a bunch of planehopping interspersed within.