serpantino: Yeah Francesco's mod is a great improvement... lets you customize a lot of things such as the night/day cycles and also lets you have non-scaling enemies (it gets dull when every enemy you meet is an equal match.)
Waltorious: I also love Francesco's mod; it's the only mod I would consider essential. I prefer it to Oscuro's Oblivion Overhaul because Francesco's is modular, and lets you install only those things that you want. If you only want to fix the level scaling (which is the main feature) you can do that and nothing else. If you also want to add some user-made weapons and armor, you can do that. User-made monsters, you can do that too. Level up more slowly, so you're not maxed out before the end? You can add that. How about some day/night cycle tweaks? Each piece is independent and can be mixed and matched to get what you want.
To my knowledge, Oscuro's does not have this modular feature. So you either have to want EVERYTHING in the mod (and it's a big mod) or you can't use it. But I have never used it, so someone please correct me if I am wrong about this.
You might want to get some of the body replacers if you are planning on adding a lot of user-made armor and clothing to the game. A lot of that equipment is designed to fit on the user-made body meshes rather than the original. I think that Robert's Male Body and Robert's Female Body are considered the best, but I have not checked in a while. Beware, these body replacer mods have nude options, but they have clothed versions too.
People have already mentioned the UI mods which are good to have too. I used a really old one called BTMod that kept the same color scheme but made the text smaller and allowed you to view more items at once in the inventory. Most people seem to prefer either DarkUI or DarnUI, neither of which I have tried myself.
I also like Darker Dungeons, which makes dungeons really dark and forces you to use a torch. But it might be a little game-breaking for a sneaky character who would have too easy of a time sneaking around in the dark. So only use it if you're not playing a sneaky character.
On Francesco : yes, the modularity of it is very very enjoyable. The problem is that some of those functionality are now better managed by more recent mods. So I generally install a "barebone" Francesco's i.e. without the day length or leveling options.
OOO is pretty modular too, in its last version. You can now choose if you want or not options like Living Economy or Harvest Flora (a great mod that visually removes parts of plants you harvested, showing you that you harvested them and you don't have to bother about them until the next season). The thing is that, for OOO too, those options are most of the time outdated. That's the problem about compilations mods. But you can still install OOO, canceling the install of those options and then install up-to-date versions of those options later.
Here's my base for Oblivion modding :
- Obilivion Mod Manager
- Wrye Bash (its Bashed Patch feature really helps to solve compatibility problems when you have lots of mods)
- OOO+Francesco+Martigern Monster Mod+Oblivion Warcry+FCOM : the base for the complete Oblivion Overhaul.
- Darnified DarkUI : one of the best interfaces out there.
- Animated Windows and Lighting System : the best lighting overhaul
- All Natural : a complete overhaul of the climate system
- Realisitc Leveling (to manage your XP progression) ; there are other good alternatives, like Oblivion XP, nGCD, Progress, etc...
- Enhanced Economy : complete overhaul of the economy.
- Robert Male's Body and Exnem HGEC female body : two of the best mods for body replacers.
- Map Marker Overhaul : a great overhaul of the functionality of the map system, lets you write your own labels, lets you display exactly the categories you want to see, lets you manage if you want to enable fast travel or not.
- Race Balancing Project : overhaul of the existing races with a complete rebalance, with also a complete rebalance of the zodiac signs and the professions.
That's what I consider as an absolute must. All the other mods, texture packs, etc. are, in my opinion, optional. But lots of them are excellent and deserve your attention too! ^_^