might be kind of a boring pick, but Donkey Kong. I know the chances of a Nintendo game on a Microsoft "community" are kinda slim, but hey we had Solid Snake in SSBB and Sonic on 360, so maybe it's Nintendo & Microsoft's turn to collaborate?
I mentioned Kung Fu Master in another thread already. But, new thread, new moment, new mind!
I have some good memories from playing Side-Arms in a Manchester arcade but if I had to choose just one game then right at this very moment I'll go with Jackal. No, Commando. No Jackal!! No!!... Comma......