Pendragon and The Great Pendragon Campaign! At least, most of it anyway as ideally it would be one year per session and the campaign is 80 years long...so yeah, that would be my first pick. Of course there would be the caveat that rule #4 would probably be broken as players would definitely have multiple PCs as their original PC will age out if they are really lucky, but is more likely to die in glorious fashion and need to be replaced. If nothing else, PCs could at best be restricted to members of the same extended family.
My second option would be Mythras and the Mythic Britain setting. I can't state enough how much I love Mythic Britain as a setting with it's a-historical "Dark Ages King Arthur" and Saxon invasion in post-Roman Britain deal. It would also be dependent on being able to break rule #4 as Mythras also has a lethal combat engine.
Honorable mentions would go to a long running Burning Wheel campaign. Though I'm not sure if I could sustain such an endeavor as a GM as BW is an much more intense experience than most TTRPGs offer. Perhaps a long running Mythras game in a homebrew setting, where I would go for more of a Game Of Thrones vibe instead of the typical fantasy adventurers. The PCs would all be folks in positions of power and influence, so politics and intrigue over combat and exploration. Or, just for something different, a Samurai Of Legend game, set in the Heian period. It would be fun to play a long campaign in a setting that is not eurocentric.
Anyway, my rambling answer. Cheers!