I’d have to say DE Star Wars. That game goes from anemic to Holy Grail with PinSound and flipper fidelity speakers.
Tron is also up there, the cosmetic mods to these 2 games bring them to an entirely new level.
The presence of a game is half the joy of it! When you feel disconnected, it’s trash. When you feel like the Grand Champion of pinball, and the pin is singing songs of praise, it becomes unparalleled.