Why ask this here? On this forum? Let me point you to the right place. http://www.nexusmods.com/oblivion/mods/top/?
So what ? He can't ask about user experiences on a mod in the actual PC gaming section of this forum ? This IS the right place to ask such questions.
Oblivion there are lots of mods, look out for any Overhaul Mods. Same for New Vegas, also try nVamp for New Vegas as that has loads of mods rolled into one.
I personally loved Oscuro's Oblivion Overhaul. It made the game far more challenging and rewarding. It's definitely a bit hardcore. Oblivion was so easy as it was though, it needed some teeth, and this mod has teeth in spades. Oscuro's Oblivion Overhaul @ Nexus Mods
As alternatives to OOO (^the above) check out Francesco's and Martigen's Monster Mod + Qarl's Texture packs are great. I can't comment on New Vegas yet since it's still on my backlist.
For Oblivion: - the ones mentioned above - Deadly reflex 6; this overhauls combat and makes it more fun and extremely violent
I Tried UVIII but it had this weird free cam "ARMA" camera glitch. Also im really wanting total high res textures, clothing and skin replacements, texture replacements, parralax stuff and how to get good performance out of both.
Probably directing him elsewhere because modding Oblivion is such an expansive undertaking. I spent three hours one night just installing the game and setting up a mod-friendly infrastructure.
Just 3 hours? It took more than that to set up the base game as well as setting up the textures mod and several UI mod for the base games. Than you will have to decide on what feature mod you want to enhance the base game and then the total game changer mod. That is a massive amount of works!
This forum taught me that no matter how you mod Oblivion, all the Khajiit NPC's have their dongs flapping in the wind. Good luck.
Yeah, I wasn't even counting the minimal amount of ACTUAL mods I actually put in, which was just like 3 or 4. Only wanted to improve the base games visuals. Some texture mods, character overhaul, ENB series..
Yeah I heard MMM was good... There's also a version for Fallout 3, but not NV, kinda of got burned by that stage.
http://www.nexusmods.com/oblivion/mods/44676/? This one is a must have. After I tried it, I found out Oblivion being pretty much unplayable without it. Also, a good ENB preset can provide miracles for this game, even more than a lot of "pseudo-Hires-textures" out on nexus can do (people who resizes vanilla textures to a higher resolution and apply a sharp filter, totally disgusting). There is some good texture replacers for Oblivion, but IMHO not in the same quality as some Skyrim ones. You will loose some time in order to find out those which really worth the trouble.
I went with the 1.0 version, its a good enough improvement over the base character models, and a lot easier to install. For ENB I have an SSAO/SMAA Only configuration. Didn't really want post-processing overkill, just something to make the world pop a little more.