The National - Boxer. Greatest evolution in sound goes to these guys from Alligator to Boxer. Two fantastic albums-- but the maturity that appeared on Boxer makes it their best album, and my favorite album of all time.
BTBAM - Colors. Also the culmination of this band's sound for me.
Fair to Midland - Fables from a Mayfly: What I Tell You Three Times is True. One of the most creative bands ever. So disappointed they disbanded.
Mastodon - Crack the Skye. Same as you, Kotow, but I think CTS inches out Leviathan just a bit. Such an immersive album.
Fall of Efrafa - Elil. The best post-metal band who ever existed imo, whose trilogy of albums is just near perfect.
Interpol - Turn on the Bright Lights. What a phenomenal album with such great atmosphere. Shame they haven't captured the same feeling again, though they came really close with their newest album.
Bon Iver - For Emma, Forever Ago. The most emotional album for me. It channels so many different facets of emotion, and really presents Vernon at his rawest, most real.
Haken - The Mountain. Everyone knows how much I love this album. A capella, beautiful melodies, crazy experimentation-- Haken's best yet.
Godspeed You! Black Emperor - Slow Riot for New Zero Kanada. Though technically an EP, this is still their strongest release for me. Passion in both songs, emotion at its highest, and such a bleak atmosphere overall.
Anathema - Weather Systems. Again, great emotion, great atmosphere, beautiful vocals,
August Burns Red - Found in Far Away Places. At the moment, I like this album more than Constellations, my fav by them. The experimentation is great and the passion is just so strong throughout the album.
Frightened Rabbit - The Midnight Organ Fight. The best post-breakup album out there. So emotional, so powerful, so real.