I actually like the look of the stock Oblivion textures, there are just some I like at a slightly higher resolution. And I'm somewhat frugal with my FPS. So maybe we share similar tastes in this regard. With that said, here is my list:
http://planetelderscrolls.gamespy.com/View.php?view=oblivionmods.detail&id=3813 - If you are willing to weed through a bit, just pick some of them, and use only the color/diffuse maps, no meshes or normal maps. This will get you slightly more vivid colors and resolution without the porousness, and you can use Bomret's normals under them if you like them, though you may have to test and make sure they still line up. I recommend:
- everything in the wood folder
- the door and wood floor/wood beam/wood post textures in their respective architecture subfolders
- copper*.dds and anvilconcrete from the architecture\anvil folder, with normal maps
- the farmhouse textures
- the chorrol wallstone and woodpanel textures
- the stonewall textures for fencing
- the rugs, in their respective clutter subfolders
- daedric statues
- the tilledsoil texture from the landscape folder, I really just dislike the vanilla one
- shipsail from the ships folder
- the fortruins textures, if you can afford them, this can get dicey in some locations
http://www.tesnexus.com/downloads/file.php?id=5570, of course, and http://www.tesnexus.com/downloads/file.php?id=16747 since you're at it. You can use http://www.tesnexus.com/downloads/file.php?id=29358 to replace the covers on all books/static booksets in mods not covered by Book Jackets, or use it instead of Book Jackets if you get an FPS drain in library-type areas. Just the espless replacer alone will not hurt performance.
The performance impact from these will be trivial or none:
http://www.tesnexus.com/downloads/file.php?id=16533 - See screenshots, just awesome for screenshots, but not invasive during gameplay.
http://www.tesnexus.com/downloads/file.php?id=23372 - Don't use if you go with OBGE's Liquid Water, but with any other water mod, use this. Makes it so distant water reflections are blurry instead of blocky, like wind over the water.
http://www.tesnexus.com/downloads/file.php?id=23064 - My favorite non-OBGE water.
http://www.tesnexus.com/downloads/file.php?id=25314 - Replaces many store signs with unique ones that were all painted in the vanilla-style.
http://www.tesnexus.com/downloads/file.php?id=14342 - Read the tin.
Slof's Horses Base (available at Wolflore and Slof's Hive), use the included plugins to get extra unique horses and cover vanilla horses, and use http://www.tesnexus.com/downloads/file.php?id=27675 to cover vanilla model horses added by mods.
http://tesalliance.org/forums/index.php?/files/file/1012-insanitys-cave-retexture/ - Fairly high-rez, but caves don't usually have a lot of other things going on to drain FPS, so you likely won't notice a perfomance drop. Worth it anyhow.
http://tesalliance.org/forums/index.php?/files/file/1035-insanitys-lod-texture-replacement/ - Not too high rez, and definitely worth it. Pair with http://www.tesnexus.com/downloads/file.php?id=9952, I recommend medium.
http://planetelderscrolls.gamespy.com/View.php?view=oblivionmods.detail&id=3588 - Not super high rez, but definitely detailed, and ruined. I love them.
http://tesalliance.org/forums/index.php?/files/file/726-snow-texture-replacer/ - I consider this a must-have.
Amp's God Statues, if you can find them!