Well, you probably already know most of my thoughts, but I'll do a list of brief things:
+ The murder mystery style questing of Oblivion, and a thrilling storyline that takes you in multiple directions (with the player's consent). Also, must be followable from the start.
+ Easy to find Daedric shrines, easier requirements and engaging quests from them.
+ A zone we haven't seen before, full of tensions (like the Orcs and their hatred for.... everyone, in Orsinium)
+ Repentance for the sin that was utterly destroying the quests of Skyrim. How about restoration of the Dark Brotherhood, which didn't feel like a generic kill quest spree like the end of the questline in Oblivion?
+ Fixed textures and carefully designed DLC
- Shouting. The sooner those memes end, the better. Not to mention it didn't do that much for gameplay in general.
.- The use of Kinect. With shouts gone, I don't need Kinect when a controller works much faster and more reliable.
- The talent tree system. I like customization but not when it's done as badly as this. A better hybrid system was in Two Worlds or heck, even Rift. True, it leads to farming but jumping doesn't give you the advantage in combat over a mud crab.
That's just a brief idea as to what I want/don't want in the next game (not inc. the MMO). Hope this inspires some more answers for your question ^^