I have been thinking about where to go with the gods system for the past few days. The thing I had before was a menu that let you pick an effect each time you prayed and the list of possibilities got longer and longer as you gained more piety. The more powerful the prayer, the longer the prayer timer would be (time until you could pray again). I think some of the prayers also drained your piety. The system was only a proof on concept; I don't think anyone wants to gods to be as bland as that system ended up being. It was basically a menu of common effects (angels, randomly generated gifts, new limbs, harden aligned material) along with their signature effects they have today.
Right now I think Mellis is the most powerful god and the reasons why are informing my plan for how to revamp the religions. Let's talk about Mellis for a bit while I continue to ruminate, so that I can be more confident that I'm not just a strange player who doesn't like pets enough or something.
1) Mellis prayers are always useful. You don't have to be in special (probably dangerous) circumstances (monsters adjacent, low on life, etc.) to get the most out of him. Just hoard all the containers you find and pray every 2.5 hours on the dot.
2) Mellis does not require any micromanagement. I love Loraticus, but to get the best use out of him you have to do things like unequip your boots, make sure they don't have blood on them, and wield them, then pray. Then put your weapons back and put your boots back on. Incidentally, I fixed this before so that he attempts to harden all of your equipment if he can't do one of his current actions. But that code is gone, so he's annoying to me.
3) Mellis prayers are better at many things you want than other gods. Some gods heal you, but Mellis lets you save up as much healing as you care to hang on to by giving you healing liquid and troll blood. Some gods can feed you, but I guarantee you'll never be hungry if you have cans and are pals with Mellis. Sometimes he'll even give you on demand (possibly permanent-able) ESP through cans of floating eye. Sometimes he'll even give you Ommel food and beverages! No extra cost, just pray a lot!
4) Mellis can substitute for effects that other gods surpass him in. I've read about Legifer being useful for knocking down walls. Mellis gives you sulfuric acid, so you can pretty much always break a couple of walls by splitting a bottle of that. How often do you really need to make a bigger hole? Throw poison on enemies with Nefas? Just dip your weapon.
The uniting theme is that Mellis lets you save up power for when you need it and burn through it as rapidly as you need to. Other gods can give you good things, but you can't save up haste from Cleptia or be teleported repeatedly from Sophos.
I think they prayer system either needs to nerf Mellis hard or allow you to get useful effects from your gods always. I'd like to hear other peoples thoughts on this before I try to address any of the issues. Powerful gods? Useless ones? Mellis isn't as great as I've made him out to be, because of X?
(BTW, I've gone through the source code of all of the gods and I think I've updated everything on the wiki
https://attnam.com/wiki/Gods.)