While the 3D Sonic the hedgehog games have a number of problems, and some of them (ESPECIALLY Shadow the hedgehog) deserve the terrible reception they got, I feel that Sonic Adventure 2 and (to a certain extent) Sonic Heroes are still very fun games. Okay, so the Eggman/Tails levels aren't great, and the treasure hunting is really annoying until you get used to it and get to know the levels better, but the Sonic/Shadow levels are a blast to (re)play, and I'd say they're the tightest 3D sonic gameplay out there. Sonic Heroes is problematic in that it's a lot more loose and a bit buggy(er)and the game makes you play through near-identical stages Four(!!!) times before giving you the final boss, I thought the team formula itself was a good idea (though it probably came as a necessity for developpers trying to plug the ridiculous overlarge character cast into the game) and I still have fun with it from time to time (bought it used, though, I wouldn't pay full retail price for that game).
Also, I've replayed it recently, and Pokemon Snap is surprisingly fun. Don't know how the actual critical reception for the game was, but I remember most people I knew bashing it for being a pokemon cash-in (which I guess it is, but it's still fun and well made).