A "skill" can be a variety of things: a talent, an ability, a strength, etc...

But to answer your question I think I'd choose the "skill" to be about absorb and retain knowledge very easily and very well. I'm a firm believer that knowledge is power and when you know everything that then paves the path toward success.

But it's that's too serious of a choice and I need to dumb it down then I'd be able to pick the "skill" then I'd choose to have the skill set of an NFL athlete because they are genetic freaks and the things they are able to do is absolutely absurd.