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.