Contest15

Eberron. I have always been interested in the Victorian Steam Punk type adventure, but never felt it worked well with a fantasy setting, which is my overall favorite genre. Eberron's "Mage Punk" concept is, in my mind, the perfect thematic combination of pseudo-science and normal fantasy tropes. Add to that the rich mythology and intrinsic presence of intrigue as part of the setting as a whole, and you have a really fun world to play in. The icing on the cake, for me especially, will always be the idea that "the players" are the great destined beings of this world, not any characters established through other mediums such as is the case with the Forgotten Realms. This emphasis on players making the stories really places it at the top of my list.

 

Judge's Guild Wilderlands
The depth and breadth of this sandbox setting is astounding. It provides a smattering of details across thousands of hexes of terrain and a rich history stretching back centuries. All of this while also not painting the GM into a corner by over-describing.

Frog God Game's Lost Lands
This setting has been developed through a series of modules by Necromancer Games and FGG over the last decade. A new series of gazetteers is tying things together and fleshing out the world. Love their work, love their adventures, love the setting so far.