What I get out of a game is all about having a fun, cinematic experience. With Bethesda games, I want to wander and explore. I rarely use Fast Travel mechanics. Usually I employ those when I am trying to finish a quest and I have a real life deadline to meet as well.
I tried all the "realism" mods for Skyrim as well as the hardcoe mode for New Vegas. They added some interesting "spreadsheet gaming" dynamics for the game, but ultimately failed on the cinematic side of things. For one thing, the mod author's view of realistic and mine often differed. Food mods, for example, seemed to demand that I have something like a 10 million calorie per day diet and constantly pestered me about eating/drinking. I ended up going with a food mod that boosted recoveries for the three main stats. Cold weather damage/hypothermia mods robbed me of the ability to explore freely, one of my favorite aspects of the game. I ended up removing the hypothermia mods altogether. I can see a point to them, but the experience created is far different than the one I want to play in.
It's hard to predict exactly what I want in Fallout 4. I know that I want a cinematic exploration game. I'll get that. It is going to be all the little details that I get to discover, as the player, that are really going to be fun. Of those, I'll probably find a few that I dislike and a few that I will wonder how I lived without. I know what I don't want (mostly the weapon degradation mechanics) and I can imagine a few mods that would be fun (expanding the powered armor to include other forms like Starcraft marines and capabilities like extended jump jets). Other than that, I'll have to tell you once the game comes out and I have had a chance to play in that sandbox for a while.