Ahhhh, the ole underpants and skinny jeans debate?
In my opinion briefs are the best option as last thing you want in 'skinny' jeans are a bunches of fabric around your crotch and ass.
As for the whether they look good or not debate, my argument about skinny jeans is they, in most cases, only look good on 'skinny' people. I mean fellas, they do what it says on the tin!! Nothing worse than heavy or muscular guys or gals 'stuffing' their goods into a pair of tailored and tapered jeans!!! The bratwurst sausage look is never a good fashion trend to follow!!!