Flight? X-Ray vision? Super strength? Regenerative abilities? Telekinesis? Mind control (These aren't the droids you are looking for)? Super speed (not so useful in the bedroom)?
You get one, which one, and why?
Me? Mind control. If you can influence anyone to do what you want, you don't need any other power, you have everyone at your will. Of course, I would only use it for good . . . I'd never use it to convince women way out of my league to have sexy time with me, nor would I use it to convince bank tellers to hand over large sums of cash. That would be an unethical use of my power.