Best game at the moment is easily Medal of Honour on the PC - the Saving Private Ryan level has some of the best set piece battles I have ever seen.
As for longeveity I think the Civilisation series of games takes some beating. I'm on version 3.0 now, but so brilliant is the core concept that I could pick up the very first version from the late '80s and still be utterly addicted. A triumph of gameplay over graphics.