[Edi]

A lot of it depends on the indie settings. I consistently play with indies 7, hard research, 100% gold and resources, magic sites 35 or less and Better Independents mod to disable the chaff.

With that setup, the EA nations that consistently come out on top with AI are the glamour nations (Van, Hel, Tuatha), Ulm, Ermor, Marverni and Sauromatia. Niefel varies a lot. Lanka is very often a strong one for the AI, but it doesn't use the blood aspect much. Tien Chi is also a fairly safe choice for the AI in that it will be at least semi-competent.

Haven't played much since 3.10 came out and never with Fomoria as an opponent, so I have no idea how that plays out. C'tis has variable success. The AI generally sucks with Abysia and isn't too competent with Arco.

MA and LA I haven't played appreciably, so no big trends, but anything that has decent armor and hits hard and straightforward is usually good for the AI.