[Sheap]

Dispossesed Spirits (havent tried those, sound pretty sucky)
Shadows (Weak! and only two a turn, even at high dominion)
Apparitions (Which require unburied corpses, so you can't mass 'em).

Dispossessed Spirits are the same as the Spirit Mastery spell, and the autosummon you get in provinces with neither temples nor forts. Which is to say, not real good, but still ethereal. And they require corpses, too. So not real good.

Shadows aren't real hot either, you don't get very many of them and they aren't very strong.

Apparitions, on the other hand, are very good. They require population (not corpses) and lots of it, but in freshly captured territory you can reanimate quite a few before everyone dies. They aren't intended as troops of the line, anyway, but more as special forces; you don't NEED millions of them. And, a level 3 priest can make them (level 4 required for horsemen), although level 4/5 are much faster.

And since for the same level of priest you need to pay more with SG and since AE has "Protection of The Sepulchre", I think AE is stronger.

Both themes have Protection of the Sepulchre, but SG needs it less. Still useful for summoned low-MR troops like Longdead Horsemen/Archers.

I find that with AE my priests spend most of their time making longdeads. With SG they spend most of their time killing things.