Many threads re worst backstabbers etc, conversely, who are the friendliest AIs??

I've found that most civ leaders will backstab you if they think they can gain an advantage or at least keep you from winning. Gandhi is one of the worst offenders. But usually he's not a threat at all. Persia too, even though surprisingly in my last game before I installed BNW Darius and I were allies until the end.

Siam ALWAYS backstabs me. I spent the late period in that game wiping him out. (The little jerk built a city on a one tile island I didn't know about so we were at war for three decades after I booted him off of the continent. It was truly cathartic to finally boot him off of the planet)

In my games on immortal and deity usually:
Brazil, Byzantium, Morocco, Iroquois, Siam, Ehtiopia, Venice

But they will still not be friends if you choose a different ideology, take their city states and lands etc.

I've had really good luck with Catherine the last few games, especially when fighting together against Oda who annoyingly plopped three cities between us extremely early even though his capital was across the continent. I've also had good relations with China, both of us voting for the other to host World Congress once [to prevent Monty from getting it].

Gustavus, Harun al-Rashid, and Casimir are also generally very friendly with me too.

Theodora, William and Kamekameha are always reasonable people, unlike that jackess Alexander....