Which game is a timeless classic for you? One that you frequently replay and never get tired of.
For me, it's the original Resident Evil. Ever since it first came out I have always found this game to be so much fun to playthrough, I've played it dozens of times on each character but still enjoy a near annual replay.
The other games in the series are good but they just don't hit the same, definitely have played this one more than all the others.