This is hard.
First pick HAS to be "Epidemic"... DAT INTRO FILL!!!
Second pick was "Angel of Death", it's a classic, can't go wrong with that.
If I hadn't played "Criminally Insane" or "Raining Blood" live a million times, one of them would be my third, but I chose "Post Mortem", it's always been a good song to just listen to.
Bummed on the lack of Aggressive Perfector though, that has always been a great track, even though it is just a Bonus Track.