StewiesTweaks takes care of most of my gameplay needs to the point that I haven't felt much need to explore other such mods. Power armor underwhelming? Stewie. Tired of inventory management? Stewie. Want pickpocket and thievery to be a more robust strategy? Believe it or not, Stewie. Hate the hacking minigame and are so incredibly good at lockpicking that it all might as well be a skill check? Stewie has it for you.
I mostly like mods that add new functionality or more content that I'll genuinely enjoy. Viva covered so many bases that there isn't much I actually want. The base game is already built around a lot of the features I would normally add into mainline Bethesda games like player choice, weapon variety, and even ammo types, so there isn't much need expand on them with poorly integrated versions of them.
The only major improvement I would want is graphical, but the outdated engine makes such improvements fundamentally limited. Besides, some of my favorite shooters are from the 90s and I don't think the graphical improvements of the last 10 years have been groundbreaking, so I'm fine with it looking worse that Source Engine games.