[Turin]

The easiest nation to play vs the AI is probably late era R´lyeh.
1)You are a water nation, so the AI can´t really invade you.
2)You get tons of freespawns, so the AI doesn´t want to declare war on you.
3)Setbacks don´t really hurt you, because of the many freespawns, which replace losses easily.
4) Your mages are very good at astral magic, which makes it easier to branch into other paths with rings of sorcery/wizardry to try out more stuff. Acashic record makes sitesearcing easy.
5) Void gate is a lot of fun.

Just make sure you take a dominion 10 pretender with good scales and you should be fine.