What races does the AI play best?

[NTJedi]

I'd say the AI plays Neifelheim as the best nation for long games... just make sure the game has very very high supply settings.

As Neifelheim its nation has access to water, air, nature, death, blood and astral. This allows the AI to find more magic sites.
On a large map where the Neifelheim AI has been provided lots of provinces and time for research you'll face battles against spells such as Mass Regeneration, Mass Protection, Anti-Magic, Doom, Wind Guide, Rush of Strength and a few others.
Now SC's is usually an easy solution to defeating the AI, however if Neifelheim is provided the time to finish it's researching SCs won't work as it will be casting "claws of kokytos".

(For smaller maps where research time is limited LA Ermor is difficult)

[Humakty]

I think the AI as real problems playing factions relying on magic to win battles, like caelum and abysia (all ages) or EA agartha.