I've always referred to him as a "Herald Buster." Team buster never made much sense to me because it depends on the team. Also, any elite herald can be a team buster. He is clearly above any herald, and that's saying a lot.
These are not complete parallels, but in terms of who might be in the general category Thanos is in, I'd say maybe Ion, a mid showing Mangog, a high end Maelstrom and perhaps a few others. The problem is those guys don't have the super human intellect, the resourcefullness, the cunning, the determination, the high end tech, the full understanding of the universe or thie history of Thanos. He's like the Dr. Doom of overloard types, punching outside of what you assume his weight level is.