Day 4 - Favorite Gameworld
I love many settings. I'm a fan of Dragonlance, Planescape, Dark Sun, Spelljammer, Forgotten Realms, Ravenloft, and Eberron. I really like Pathfinder's Golarion too (since it's basically a mix of the worlds I just mentioned). I dig the Known World/Hollow World and Greyhawk too (though I have little experience with them).
However my favorite gameworld is Green Ronin's Freeport. I can't quite pin the reason down, but I'd say it has something to do with the combination of cinematic pirate goodness and Lovecraftian horror. I've ran the Freeport trilogy and loved it (despite the horrible party make up and the fact that my players were sticks in the mud). I own almost every Freeport book (3.0, 3.5, Pathfinder, Systemless, and most of the companions). I even pledged a hundred dollars on the kickstarter this past spring. At one point I'd planned on running a Freeport game using the AGE system. I only completed one of my intended posts. However, I've read that an AGE Freeport Companion will come out in the next year or two.