These are the mods that I believe can turn FNV into a somewhat FO4. I don't play NV anymore as I've gotten sick of going to the same places over and over again. I love dragbody's work and I don't have to lie to you about it because his mods really are the sickest ones around, but for the sake of consistency throughout the NPCs in-game, armors, and lore, I chose New Vegas Redesigned.
Another thing to note, if you are looking to make FNV as action-oriented as possible like how FO4 is, its gonna be a bit of experimenting from this point on. FNV doesn't handle big amount of NPCs too well and this issue increases when you keep installing high resolution environment mods like OJO Bueno, NMC Large, etc.
Last note, I don't advise using save managers anymore because first, it takes up space in your load order and next is manual saving of the game prevents save file corruption better than having a save manager like CASM doing the work for you.
I don't play FNV anymore and I don't think I will for a long long time, but I can assure you that most of the mods and things I've said here are all based from experience and not just some data gathering. Have fun and happy modding!
- Spoiler:
Project Nevada with Extra Options
ADAM Reborn
Caesar's New Regime
Book of Steel by aMidian and darthbdaman (this is the merged version)
Wasteland HiRes Clothing
Roberts Body Replacer
Type-3 for Females
Weapon Mods Expanded
Lazarus Project
Animation Project
ExE by weijessen
Enhanced Bullet Impacts
Weapon Retexture Project
Weapon Animation Replacers OR Hitman's Animations
FNV LOD Generator (I used this a lot)
47 ENB The Sequel
EVE (if you want your energy weapons looking like its from some scifi movie or if you just want them to have some ironsights)
Wasteland Flora Overhaul
EDIT: I forgot to mention Immersive Recoil. This mod uses your stats in-game to compute for the amount of recoil you'll get per weapon. So if you plan to use the AMR early on....oh well