I've been a Mastodon fan since 2004 when I first heard Leviathan and Remission and saw the Relapse Contamination Fest DVD. I remember waiting for Blood Mountain with great expectations and although there are some amazing songs on that album, it wasn't what I expected it to get from this band at the time. But Crack the Skye, for the most part, was everything I wanted from this band after Leviathan. That album rules. The Hunter is also like Blood Mountain for me - some really great songs but not really a stand out album. I hardly even listened to Once More.
I wasn't even interested in hearing Emperor of the Sand...especially after hearing another poppy weak single from this band. But I threw it on one day and fell in love with it. I probably listened to this album 20 times in 2 weeks a few months ago. I fell asleep to it a few times. Definitely on par with Crack the Skye. I think Steambreather, Clandestiny, and Jaguar God is some of the coolest shit they have ever done. Precious Stones really gets to me as well - Brent's vocals really shine on this one. Scorpion Breath has like Remission style riffs mixed with Neurosis - Through Silver in Blood tones. Definitely didn't expect it to be so good.