Elvis from the Sun years to early 60's was definitely the most bad-ass, big-voiced, crazy-legged, white Blues singer on the planet! After the Army however... I don't know what the hell happened!
When he made his "comeback" in the late 60's, you saw a bit of the old Elvis in him, but by the 70's he changed to the "Vegas Elvis" and went downhill pretty much until his demise...