er, wouldn't Odo be the obvious choice? Probably the most powerful character, and you could experience shape-shifting into all kinds of things. And if another changeling is around, you could experience the link.
I'd be Worf and experience a day of crushing Dominion skulls and fucking Jadzia. Going back to a lifestyle of marathoning Pokemon, alone in my room, would be a bit depressing in comparison though.
I reckon being Quark for a day might be fun! Always something illegal but fun on the go, and he does seem to get a lot of action! There again, I wouldn't mind a day as Dukat either, ordering everyone around, feeling generally smug about myself and having a pick-and-choose menu of pretty Bajorans at hand for whenever I want one.. (grin)