Out of these options, Planescape, easily.
Unpopular opinion time: I am not a big fan of the Forgotten Realms. The setting is just a mash of vague fantasy "stuff" tossed into a blender with a sprinkling of overpowered Mary Sue heroes (coughcoughElminster) on top to upstage the PCs. It doesn't make much internal sense because it's constructed out of decades of writers pasting over each other, and manages to suffer from both being tied to the status quo and having cataclysmic setting changes as the march of game editions demands. I much prefer Golarion when it comes to kitchen-sink fantasy settings. Or even Greyhawk!
