Mine are:
1. Return of a Morrowind-like armor system (peace-meel?) where pauldrens, gloves, can be equipted one at a time or two different.
Would be great if it was improved over morrowind so you could equipt one of each boot as well. Also the ability to wear cloths under armor and robes/skirts over top of armor.
Also wouldn't it be great to choose where you holster your weapons ? Wear a short sword/dagger on your ankle or sideways across the small of your back.
2. Visible damages. Cuts, wounds, burn marks from fire magic, etc etc. NPCs as well as PC. Also your armor/clothes would get damaged (dents, scraqes, tears) until repaired/mended and dirty (blood/mud) until cleaned. Cuts would become scars on both NPCs (if left alive) as well as PC. Black and white 1 had this implemented on the creatures so we know it's possible.
3. MORE armor and weapons. Oblivon and morrowind just didn't cut it imo. Oblivion was worse. Helms especially. We also need more uniques (with unique models) like boots of blinding speed !
And a kill counter would be nice on weapons.
4. Realistic combat with limb specific damage. Not just health bars. If i shoot someone in the foot with 20 arrows it shouldn't kill them. One to an unarmored head should instant kill. One in the stomach might kill over time from infection. A few into the torso would probably kill. It would have limits for fun tho, it wouldn't be real world just alot realer than it is in games now. Also dismemberment on NPCs, monsters (hacking a spiders limbs off with each swing of blade), as well as the PC (rarely) getting arms and legs cut off. You could go and buy peg legs though... or maybe regrow an arm with conjuration magic (zombie arm for strength like princess monoke) or high level restoration (your old arm good as new)
5.More control. In oblivion you can crouch and walk and run. You can sit in benches and that's about it. I would like to be able to sit ANYWHERE. And lie down and crawl on the ground like metal gear solid thru a mud puddle and get all covered in mud. Climbing would be great too. It would also be cool if your character actually reached out and grabed items when moving them instead of them just hovering in front of you. Seeing your LEGSSS !!!
These are all possible and have been in games in some fashion or another for years now. I was going to put a "chohesive world" with no between any dungeons or buildings in the entire game, but i doubt it's possible with these consoles. IT would be sweet tho. Hording a corpse pile in your house for later eating (cannibal kajit roleplaying) or taking the heads of slain foes and stringing them on your shelf like trophies!