I somewhat prefer to DM. Having played with 2 DMs, I really liked the one that had the inconvienently scheduled game (in the homebrew that he was consistently interested in). Go figure. But even then, I found that sometimes I really just wanted to swap characters for a more interesting build -- and being a DM gives me the chance to build things as interesting as my poor little players can handle.
Doppelganger vampire monks that go ethereal instead of gaseous...
Insane half-golem trolls...
Chimeric Yuan-Ti abominations...
Large half-fiend Gibbering Mouthers...
A demon chicken named Mr. Tiiba, based on the Vrock...
A Spirit Naga advanced to Huge size that cast Girallon's Blessing on herself to get 6 arms and look just like a certain demon with substantially higher CR....
And for all of that, the only guys that managed to kill a party memeber were the boring old clerics.
DMing is fun. Build as much as you want and it's a good thing when it dies.
::Kaze