The ones that stick to Vanilla but simply improve visuals are:
HDReworked Project - This one is a MUST, they're basically higher res textures. So long as you have vram, they cost nothing in terms of performance.
Tweaks - This one doesn't change anything in the game, it simply gives you more options in the in-game menu to change things rather than having to edit the ini config.
All Quest Objectives on Map - This one changes map so that it has more info on it in terms of icons. It is a BIG quality of life improvement.
HD Monsters Reworked - In the same spirit as HDRP above it, this is a graphical update to monsters without actually changing how they look generally from vanilla. More of getting them to a higher-res level than anything else.
Beautiful Grass - This just changes grass, but only for vanilla not expacs.
Blood - Improves blood, it sprays more and in a more dramatic fashion.
No Dirty Lens - Basically what is says, you don't get dirty screen effect anymore.
Improved Signs - Ups the GFX of signs, particularly particle count.
Increased Draw Distance - As the name says. For me it's a must have because I'm very particular about this setting & can never get enough. Also only for Vanilla, though there's a Toussaint version supposedly.
Auto-Apply Oils - It does a scan around you for enemies and based on their type it automatically applies the relevant oil to your weapon. It's both greatly convenient & somewhat iffy because it feels like too much convenience almost. Sadly, I think ultimately this is down to a game design problem where oils sounded good in theory & were appropriate to the lore but just didn't make sense as a game system as it is. Since they're not going to rework it, I say just use the mod.
At the very least install HDReworked Project, it honestly should be bundled with the game.
