I like the underrated thread because it's a nice way to recommend games that didn't receive the commercial or critical success they deserved, negative threads like this of people listing mostly liked/loved games they feel don't deserve their acclaimed or fandom seems to benefit nobody in my opinion.
Anyway, games that rated very well (86%+) that I would rate 85% or lower:
Halo 3 & 4, Killzone 2, Uncharted 1 & 3, Resistance 2, Fallout 3, MGS4, Heavy Rain, GTA IV, Bayonetta (actually any well received Japanese game since I just don't like them)... There's a lot but I can't be bothered to list any more.