Just some more feedback from solo play, specifically the civs that consistently do well.
Ljolsalfar
Lanun
Khazad
All three of these seem to frequently become steamroller empires in the late game. I have never seen any of those civs take any religion but their default religions playing this mod, at least I have never noticed them with anything but the usual for them.
Most of the civs seem like they become pretty good. For some odd reason the Svartalfar do terribly in most games. If the Luchiurp make it past the first 200 rounds they become very, very strong.
It does seem like a Runes/Fellowship world. Most civs other than the Lanun don't seem to do too well with the overlords. None of the ai civs seem to know what to do with the Empyrean.
For most of the civs besides the Lanun and Khazad (Luchiurp too, I don't think I've ever seen them as anything but Runes), they seem to do best with the Fellowship. The Kilomorph units might be better, but the Fellowship civs seem to get lots of large productive cities with that religion. It just seems to outweigh the benefits of the Kilomorph religion.
I don't think the Order is very popular with the ai's for some reason. Civs seem far more likely to go for the Ashen Veil or even Esus than that one. Most of the time it seems like the Bannor go Runes, along with the Elohim. Sometimes the Elohim will switch to Empyrean later, but quite often the stay Runes the whole way.
As a player, I find it much easier to defeat civs that have any religion but Runes or the Fellowship. Well the Lanun are hard, because it is a job to deal with all the cities they wind up with.
Just to summarize my thoughts:
Some civs never take anything but certain religions, ever.
Khazad - Runes
Luchiurp - Runes
Lanun - OO
Ljolsalfar - Fellowship
Civs that usually go for the Fellowship
Svarts (sometimes they take the Veil, but they are awful with anything but this)
Doviello (sometimes the Veil. Usually the Leaves though. Never seen them with anything but these two.)
Civs that usually go for the Runes:
Bannor
Elohim
Sidhar (for some reason)
The Kuriotates are a little more likely to take the Fellowhip than Runes, but I've seen them with both. If they are Fellowship they are far tougher to deal with.
I don't know about the Balseraphs. I kill them immediately because I hate Loki, if they start next to me. They can be tough later on, but I think even the ai hates them. If for some reason they make it to the late game I've seen them with Leaves and Ashen Veil. Never Runes or anything else.
Civs seem to go for Esus to build Nox Noctis, but seldom make that the state religion. Or maybe I'm not noticing. You do see Nighwatch all over the place though.
As a rule of thumb, this is the order of Religions that are difficult to deal with from hard to easy:
Fellowship
Runes
Octopus Overlords
Ashen Veil
Order/Empyrean as a tie for last place
The ai isn't very good at using the Empyrean. That religion is pretty much just blinding light and Chalid. And the ai doesn't handle either very well. With ice mana being out there more commonly, this isn't such a big deal anymore.
The Order just doesn't seem to benefit the ai. As a player they seem pretty weak when I use them. Sphener just seems to come too late. As an early hero Valin just never has been too good for me. I've gotten a lot more use out of Bambur and Saverous for some reason. I'm not sure why that is the case, other than that they can use metal weapons for an upgrade.
Then too, the mage heroes seem to be hard for the ai to use effectively. Every game it seems like I see Bambur and Saverous pounding on things all game long. Hemah and Gibbon never seem to make much difference.
Rosier usually dies pretty quickly for some reason. Kyra Kyriel seems like he is the best of the mounted religious heroes. Mardero usually seems to die pretty quickly when he comes up.
Really the early heroes are far more important than the later ones.