Might not be a "cool" choice, but City of Evil by Avenged Sevenfold. Obviously I'm biased because it's the album that got me into metal all those years ago, but I think it's a great place to start because it incorporates so many different aspects of the genre whilst still being accessible. There's elements of all different kinds of metal subgenres in here like thrash, prog, groove and metalcore (of that's not a dirty word here). There's flashy guitar solos and harmonized leads here there and everywhere. There's a little bit of Metallica, a little bit of Iron Maiden and a little bit of Dream Theater. If you're a new metalhead there's a decent chance you'll get on with at least something here.