Xena Warrior Princess - XENA! Perhaps not for some of the reasons others might note, but because she got to play opposite some fantastic fellas. ;) And really, Xena is full of such depth and complexity, who would not want to play her? Plus all that leather rocks.
Dark Angel - MAX. Another kickass gal, though younger. LOL! Or if there were another X5 gal, that would be cool too. Must be the one with superhuman powers.
Star Trek: The Next Generation - DEANNA TROI. I always loved the Betazoid thing and the underlying love between her and Will Riker. I found her a fascinating character. And beautiful.
CSI - MANDY or JESSIE. Actually, I'll take being any of the lab rats on CSI. Mandy because Nick sings to her and Jessie because she's the animal gal. :)
The Office - PAM. Because I have her job right now. Receptionist. LOL!