Deadly Reflex makes melee combat more realistic and gory, newest version includes weapon throwing and kicks.
Duke Patricks Combat Archery makes archery much more realistic and fun.
Duke Patricks Basic hypothermia major immersion mod, click the link for details.
Immersive Interiors allows you to look out windows.
Cyrodiil NPCs Remodeling Project overhauls npc clothes and inventories with immersion in mind rather than slutty or stylish. The mods on nexus but its massive and broken into many parts so just check the creator's profile
Vim and Vigor Advanced is essentially a role-player's "realism" mod. It is designed to simulate the need for food, water and sleep
COBL you probably already know what it is.
All Natural is best weather mod out there.
ROM overhaul an OOO inspired overhaul with a focus on immersion and stealth but I'm not a fan of the melee combat system it uses.
Nehrim Total conversion takes inspiration from Gothic and OOO and is much more role-player and immersionist friendly then vanilla oblivion; but you'll still want to add some mods to it.