Mastodon is my all time favorite band, I love all of the music that they have put out. What you have to realize is the amazing progression this band went through. They had major metal and hardcore influences but eventually became more and more progressive. Crack the Skye (their most recent effort) was super progressive and not particularly metal but it is such a wonderful album that nobody can deny it.
Trivium on the other hand doesn't really do anything for me. if you want good METAL stay away from Trivium, they're almost a pop band.
Best bands that are actually part of that movement are going to have to be Mastodon, Lamb of god and DevilDriver.
If you look at the list
a lot of those are "Numetal" or "Hardcore" bands.