Okay, I try not to mention this too often for fear of being "the dude who only talks about Farscape" but…
I would say that Farscape is quite underrated as a TV series. When people see it, usually they think of it as just another Star Trek clone, or they see that was was made by The Jim Henson Company and immediately think it's Muppets in space, which couldn't be further from the truth on both counts. While it does feature animatronic puppet characters, they are so well made and operated they emote better than most A-List actors! Granted, it did get a bit weird in places, but it was one of the most well written, best acted and had the most engaging story lines I've ever seen in a TV show.
As for other things, well the music group Supreme Beings Of Leisure are pretty underrated, so much so I've never met another person who's even heard of them, lol!
And I agree that Ratchet can be a bit, as well. I think most people would probably just see it as a kids game, when clearly it's not