I remember when Blood Mountain came out and Mastodon was being pushed as the next best thing. I bought the CD, having only listened to "The wolf Is Loose" (which I thought was pretty awesome) and I hated most of the album. Cut '09 and I hear "Oblivion" and I thought it was fucking awesome. I loved Brann's vocals so that was a great way to help me get used to Brent and Troy's rather unique vocals.
It took a while, but I eventually really got into CTS and I love it now. Went back and listened to Leviathan, BM and Remission. Leviathan I loved almost immediately. BM eventually grew on me to the point that I do like it now, but it's still one of my least favorites from them. Remission is about half good and half completely forgettable. I liked their heavier stuff, but on Remission, the songs just weren't that interesting.
Finally The Hunter came out and I was bit torn on it at first. It seemed good, but not awesome. It almost sounded like Mastodon's Black Album, though nowhere near as boring. It eventually grew on me. The Hunter has a lot of really quality songs but I hope that this is not a style that they stick with for very long.
My Ranking:
Crack The Skye
Leviathan
--- Those two are incredibly close. Really amazing albums right there. ---
The Hunter
Blood Mountain
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Remission