I picked 4e, but I also could have picked "Other Systems."
I DM several RPGs, because no single RPG can scratch all my gaming itches at once. Right now, I'm DMing 4e, 1e, and (soon) Call of Cthulhu d20, which I've also run before. In the past year or two, I've also run 3.5e, WFRP2e and SWSE.
I'm in no hurry to DM a normal 3e game again anytime soon, but I'd certainly play in one. I burned out while making encounters and NPCs for an Arcana Evolved game... I also think I'd need to houserule SWSE fairly extensively to be happy running it, right now. Specifically, I'd want a large overhaul of the Force rules so that it's no longer a skill check; and I'd want to implement the 4e combat actions system in some respect.
-O