Well, the obvious thing I'd like is another Planescape game. Definitely not Planescape: Torment 2 but still Planescape: Something.
If original IP would be preferred/necessitated by license troubles, then I have a simple request: keep it way out there. No vanilla sci-fi/fantasy, no burdening yourself to make it "realistic" or down to earth.
And perhaps the most important thing, that I assume is obvious to you, but I'll still say it: I hope you're treating all this questioning the fans as a loose hunt for ideas, not as simply surveying what's most popular. Just make what you guys want to make - you have enough of our trust for that.
Good luck.