3Miro
Deity
Semi-bugreport: as the French, I conquered, Poznan which gave me 25 stability points instantly. I switched to imperialism a while ago, so I assume it had something to do with this? I've got quite a few cities in this save (Napoleon would be jealous) so I think the game updated the stability bonus at the time I got a new city.
By the way, I shouldn't be at +60 stability at this point of the game. Does someone else find the current system too forgiving? Because this is a rather long game the only civs I've tried so far are Moscow and France (not the hardest to get a large empire), but nevertheless I have the feeling that it should be a bit harder to expand.
This is the combination of Imperialism + French UP that gives you about 50 extra stability points. I will nerf that (cap it).