Enumerated, but randomly and not by importance:
1. QTP 1.3 Redimized if your graphics card is up for it.
2. Better Cities, if your CPU is up for it.
3. Unnecessary Violence II (I can't stop marveling at what was able to be accomplished in that mod).
4. Deadly Reflex 6
5. Companion Vilja (and my personal favorite, Vilja as Moonshadow Elf from the customization pack)
6. Kinda hesitant to put this but so far it's working on my system: VORB. Adds some variety to the female NPCs; anything that breaks the monotony of character models in a video game is great for me.
7. OBGE Liquid Water (if your graphics card can handle it)
8. Let The People Drink!
9. The Imperial Waters (goes great with 8).
10. The Duke Patrick Nosferatu Vampires mod. I'm not very far into the game yet but I've run into one vampire so far... They can do some scary stuff with that mod. I ran for it as the vamp killed the guardsman that came to defend me.
I'm all over UV II right now, and I'm sure it'll only get better as some of the early bugs are fixed. It's very polished for a first release and adds a bunch of fun to the game; I've been wanting to play a dual-wielding battlemage since the mod was announced a year ago, and now I can