This is definitely where my interests are starting to lean in terms of prog stuff. Don't get me wrong, I like a lot of what prog metal is doing in it's own "mainstream" right now, but this kind of stuff breaks out from the homogeny of it all and adds a nice departure from the Axe-FX crowd.
That said, misterhustle24's list is pretty damn spot-on. Things I would add, though
This is my favorite Russian Circles album. Memorial is good, but there's something about both Enter and Station that make them stand out above the rest of their discography, to me.
This Pelican song (What We All Come to Need) is fantastic. This whole album is pretty on-point, and to be honest, City of Echoes is my personal favorite album from them, but this song just hits the spot for me pretty regularly.
Baroness. I'm going to assume you already know Baroness. If not, enjoy!
Irepress. These guys are probably a little bit more outside the sludgy, posty sound of a lot of these bands, but they still fit, and are fantastic
Lumbar. To really get this band, you have to know the backstory. It's all available with a little bit of googling, but TL;DR: Dude who wrote the album has MS, and the music/lyrics are written about his daily struggle with the disease. Very powerful stuff.
SUMA. Maybe not as proggy as some other acts, but still worth a listen.
Tides. I'm pretty sure this band is RIP, which sucks because this album ruled.
I know many more that fit more and less inside the "prog" and "post" aspects, if you're interested, too.