Very hard decision, I mean the one I played most and still play with a few friends is in fact "Shadowrun" (2e - 6e), but I have to confess, I never joked about Cyberpunk players, I even played Cyberpunk, sometimes both on the same weekend (weird, right).

Here are the three that I remember having the most fun with:

1. "Magna Veritas" and "In Nomine Satanis" (originally from France, iirc), where you played Angels vs Daemons (think "Good Omens" just even more absurd).

2. There was one called "Plüsch, Power und Plunder" where you played living plushies, and had to hide the fact that you're alive from humans.

3. "Paranoia", a game where just surviving was the adventure in a dystopian social credit system, that executed you immediately with killer drones, when you got demoted to the lowest level "Infrared", but you could just use a new clone and start again.

The most rounded rule system I ever expierienced is ERPS, no levels, no experience, just using the skills/attributes give you a change of increasing that particular attribute or skill (this is also free, but only available in German iirc).