Overrated: Tanahashi. I have no problem with people liking him, and he's not someone where I am completely clueless as to why he appeals to people, but he's a guy some people talk about as an absolute upper tier all time worker on par with the All Japan guys, the best guys from the States, et. I don't think he'd make my top 1000, and that's with me enjoyed him in the last 10-12 months more than any previous period of his career.
Underrated: Flip a coin between all Puerto Rican wrestling and lucha. Lucha has gotten a bit of a bump in recent years (or at least it feels like it), so maybe I'd go with PR, a promotion that was probably the best gimmick match promotions of all time, featured a shit ton of good matches, some tremendous matches, some all time great feuds, et.