Nothing. You get green text and the ability to talk to the Community Managers in discord from time to time. Mostly MVPs talk to each other, if they talk at all.
There is also no requirement to agree with or like Blizzard stuff. We just have to express criticism constructively instead of going off on a rant and wanting people fired. That also tends to mean that an MVP or CC member disagreeing with Blizz or not liking something, goes un-noticed. It does not get the attention that internet outrage does.
The people in the current MVP program have a wide variety of interests. Some raid, some really like transmog and used to make transmog guides, another ran friendship moose, one is very very PvP oriented. Etc. I guess I am just general purpose casual.