I always try to land it. First off, I don't always know when I get a kill or assist and not even notice it. Second, and more importantly, the flight home is often one of the most fun parts of a flight.
Trying to limp home a P38 with a pilot wound, missing left wing, dead right engine, missing right aerilon, damaged gear and flaps punctured fuel tank and trying to get belly down on the runway right before the black tunnel of doom closes in on me when I'm 10 feet over the ground...
that's a rush to me =)