Math Metal and Post-Metal are the pinnacle and standard of all metal music.

What can you recommend from the post-metal genre?

The coolest are Isis (they are the originators of the style, by the way), and Rosetta too...
The style is quite blurred now; I've even encountered Post-Black / Post-Metal (I don't remember the band) or Post-Metal / Post-Hardcore / Mathcore ("Plebeian Grandstand")

Added 7 minutes later

Lamb of God. It's a rather ambiguous style. Some say it's melodic death (although it doesn't really resemble it), some say it's groove metal, and some call it post-thrash metal. But it's a quality band.

Definitely a good band, I like the rhythmic elements, and I don't understand why people started confusing melodic death with metalcore (although they are similar). Lamb of God is Metalcore / Groove; it's a shame that the guys don't play technical metalcore.