Out of the traditional 5, I would probably give up...wow they all rule. Maybe smell -- though I don't think I would function well without it. However I'm so hedonistic with the rest.

Sense of pain (but not touch) would be good. I could give up masochism for basically limitless pain threshold.

So that.

As for made up sense, I'm already lacking any common sense so let's just keep running with that.