I'm not quite sure why, but for some reason Metalcore (wikipedia) sounds to me the way I expect Heavy Metal to sound.  It's brash, driving, aggressive, yet also dynamic and at times melodic.  Metalcore is itself only arguably a distinct subgenre (Allmusic doesn't consider it separately), and it certainly represents a blend of its two namesake influences, Metal and Hardcore Punk.  While permeated with the speed and ferocity of Thrash, and the screams and growls of Death Metal, Metalcore is more likely to have a social conscience than many kinds of metal (related to its Hardcore antecedents).  As with so many Metal artists, those mentioned below may transcend subgenre boundaries, but I think the tracks I've listed, at least, do represent Metalcore well.  As is evident by the list of favorite tracks below, I quite enjoy Metalcore (a bit of a surprise to me, I'll admit)...definitely one of my favorite flavors of Heavy Metal.