The Sony MDR-7506 gets a lot of mentions every time this question comes up, at least from sources I read/trust. I don't own a pair.
I have purchased A LOT of different sets between $60 and $130 (HiFiMan Edition S, Sennheiser PX-200II, B&W P3 Series II), and I think the Monoprice 8323 cans, which can be had from the website for something like $17 (plus shipping) is as-good-or-better-than almost every other (sub $130-and-no-amp-needed) set I've ever tried. TIFWIW. They won't be "cool" with your friends the way Beats By Dre will be, but if you're serious about wanting to get a taste of "audiophile sound," at $17 it's a no-brainer purchase IMO.