I've seen a few calculations, Archers are still the cream of the crop. And sadly, Heavy Infantry is at the bottom.
Also yes, AI is bad at managing generals, at least for major battles you want to at least have balanced flanks, competent generals and that they lead compatible troops. The AI is all to happy giving all the cavalry to an Heavy Foot leader.
That isn't my issue, I always manually assign generals. My question is when I open the options for the army and hit the auto balance button for the flanks and troop composition, is the a.i. competent at doing this? It never seems like it's doing anything too stupid with that but then again I usually try to rely on overwhelming numbers and terrain modifiers.