I mostly DM - of the current 5 - all have run something, not always successfully - 
The other experianced DM runs a game on another day, with two of the people from my group.
He has run games for us, but mostly to fill in, or when I burnt out he had someone else is DMing his other group.  and ran us through CoSQ.
The youngest player ran a fine D&D game, but burnt out fast.  Her husband ran d20Modern, poorly, and the last ran a oneshot Paranoia - which started well but lacked a finish. 
I am the best long term DM the group has, and prefer it to playing.  I like the stimulation and the amount of work that goes into a game.  Last time I took more than a month off, I created a new campaign world. I think I  may be an addict.