These type of threads bother me because I know what everyone will be asking for, no weapon breaking.
Personally, I really liked the weapon breaking mechanic. It gave it a survival-esque type feeling. You couldn't rely on your weapons, sometimes you had to sneak by an encampment because it wasn't worth it. Sometimes your good weapon would break and you'd have to improvise. If that mechanic was gone I'd probably stop going for environmental kills as much (out of sheer laziness), and those can be exhilarating when done correctly!
Personally what I want are a greater amount of unique items (e.g. not just bombs, stasis, magnesis, and the ice block one). Even if that means dungeons must be taken in a more linear fashion...maybe make it half way linear. Or do the Mega Man thing and make it to where you can tackle the dungeons however you want but the boss fight is easier with a particular weapon/item in hand from a different dungeon. I do want better dungeons. I thought that the whole "open your map" dungeon mechanic was really cool the first time, but for all four of the major dungeons? Nah, I wasn't as impressed. I do want a variety of unique bosses, and I'd also love a recipe book. This way you could find recipes or discover them yourself. Then you could go to the recipe book when cooking and auto make certain things to eat or drink, so it isn't so intrusive.