> Secondarily relevant question: which existing system offers you the best probability of a satisfactory life given that random start? What features of that system make it better?

One of the Northern European social democracies is a strong bet. High-trust societies with free education, good social safety net in cast I end up in a broken family, and stable democracies with proven track record of improving the society vs. improving conditions just for the main voting populace.

I think that high-trust part is one of the most important ones if often overlooked. I think it means in practice that you don't have to worry of being ruined even if your clique doesn't win, and you don't have to second-guess everyone's true motives.