Update 2!
I added new Shaggy fur choices for horse textures, with newly adjusted feathering and mane coloring to match better. I also merged the darker white markings as an optional addon in the FOMOD.
I redid the unicorn horns from scratch, now using a modified vanilla unicorn horn mesh and textures, instead of the Roach ones. I feel these look better than the old horns, hopefully folks agree and I don't make anybody sad with the change.

Horn options are now separated choices in the FOMOD. You can make the base game's unicorn horn rainbow in color, you can give Shadowmere a gnarled red horn, and/or give all horses a smaller, bone colored (unicorn horn is by default larger and more white) horn!

I also made a patch for Knights of the Nine Revelation for the horse named Spirit, giving him unique white fur textures, unique eyes, and unique colored tack to make him different from the others. But you can also still get him armored with Steel and Elven armor from the Horse Armor DLC. He also comes with optional standalone feathering and a standalone golden unicorn horn if you want that.
I don't use KOTN Rev sadly, so there's no proper screenshots. If someone could upload some of Spirit using my mod, that'd be awesome!

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PSA: The main mod remains ESPless for capability reasons, but a kind user by the name of Camper6 has made a plugin that re-enables manes on armored horses. If you know how to work Wyre Bash and the Bashed Patch, this is a better solution than my original file method of swapping textures as you change your horses haha.

Leaving my original method as the main method however because I know a lot of people solely use Vortex or MO2, or basically anything but Wyre Bash. I use Wyre Bash through MO2 for Bashed Patch purposes though and if you wanna learn how, come join the Discord Server for OCMG, a Oblivion modding guide by Dispensation.

Just enable the ESP, make sure it's above the Bashed Patch, then rebuild your patch, let it copy the records over, then disable the ESP from the load order.
Same instructions for the Imperial Horse Armor addon.

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Hello all! Got another mod for y'all, because it's been fun now that I've learned more about how to use Outfit Studio.

This time, I was successful in the endeavor of weight painting! Which gave the horses from ROACH Horse Resource Pack proper animated ears! It's not perfect, but it's a major improvement from the complete static ears from before. 

My mod does not use anything from KatKat's port, due to closed permissions + personal reasons. Animating the ears was purely through my own work using Outfit Studio and Nifskope.

Anyway, this replacer is simple! It contains no ESP, so it's capable with all those horse utility mods and all that. All it does is replace all the vanilla horse meshes (body, head, eyes, mane, unicorn horn and so on) with assets from that resource pack. The textures meanwhile are in their own folder, so that vanilla textures remain in case another mod references them.

Textures are all relatively high quality 2K level (though the body textures are technically 2K by 4K because they are not a square file unlike most textures), though some smaller texture files are 1K and the colors were matched as closely to the vanilla horse patterns that I could, to stay faithful to the originals. 

Saddles, armor and tack were all replaced as well, with hopefully something still exciting but a bit more modest. Horse Armor is no longer full body plate, but instead a champron (like a plate of metal) on the chest, and some extra parts around the front/new colored saddle and blanket. 

The installer is a simple FOMOD that will install all base files + give you a few exciting or silly options, including adding feathering to the hooves of the horses, or making every horse in the game into a unicorn lol. There's also an optional ESP to give all Imperial legion Horses the steel armor from this mod, but that requires using Wrye Bash at least via the Bashed Patch feature.

Contains a patch for my Klen the Customizable Equine and in the future, I plan to remake the mod entirely with Roach assets and many coat options! 
You do NOT need the Klen patch if your Klen is bareback or uses the blanket option though! This is only for patching the saddles/armors option to prevent clipping.

You also do not need the horse armor DLC if you don't have it, though you won't get access to the Elven and Steel armor replacers. No DLC or anything needed, really, if you just want the vanilla replacer.

Future Plans:
Alternative pattern options
Blinking eyes
Klen remake

Recommended Mods: 
Simple Horse Utilities
Faster Horse Dismount
Smoother Horse Animations

For Simple Horse Utilities, use my patch in the main FOMOD to prevent clipping. Do not just delete the meshes from Simple Horse Utilities! Stretching will happen.

Alternatively, Horse Gameplay Overhaul is an option. I personally don't like it but my mod is capable with it. However it would replace/be incapable with all other suggested horse mods listed above.

Tools Used:
GIMP
Paint.net
Outfit Studio
Nifskope

Credits:
chakaru11 for ROACH Horse Resource Pack  (Mostly meshes and hair/mane textures)
WillOhTheWisp for Witcher Horse Expansion for Skyrim (Most of the mod's horse textures, ported with permission and not using ANY Bethesda assets.)
Feradiera for Fera's Roach and Horse Overhaul for The Witcher 3 (Textures found in WillOhTheWisp's mod, but I received permission from Fera too! Since that's where the originals came from.)
Elrian for Craftable Saddles (Tack textures)

If you wish to chat with me and/or see my other work, including early WIPs and the like, check out my discord server here! All are welcome. Coop's Nest