I thought about starting a thread of the most under-appreciated game of all time, but decided I'd rather go with this generation.

Wii - Super Paper Mario (i love this game)

360 - Star Ocean360 - Star Ocean

PS3 owners could probably better determine the PS3 choice but I have

PS3 - Bioshock (I don't understand why the PS3 audience didn't give this game alot of love)

Valkyria chronicles.

Most under appreciated this Gen?
So far...

Wii - no idea...
360 - Mass Effect
PS3 - Uncharted : Drakes Fortune

I'd say Valkyria Chronicles, Crackdown & Warhawk are all underrated/under appreciated.

ps3- Valkyria and motorstorm PR

Xbox- Tales of vesperia and star ocean

Wii-no idea.....

See my sig

If we go by sales, then the examples given already fit the bill neatly. For ratings, i would say Sonic and the Secret Rings at least on the Wii front. 

Wii - de Blob

360 - Kameo: Elements of Power

PS3 - no idea..

Under appreciated makes me think that the games chosen should be those that aren't thought of by owners of the console but should be.

I think Disgaea 3 qualifies since it doesn't get the fanfare that VC does, and many times when I see people complaining about the lack of JRPG's on PS3 they don't own either Disgaea 3 or VC, but atleast VC gets alot of fanfare from those that love it (mostly because it's the better game), but Disgaea 3 deserves more than to be ignored)

Viva Pinata