Mine is:
Better Melee/Unarmed combat:
This means the gory environmental kills! I want to see somebody's head get slammed against a wall (which would be a situational VATS move)
This also means MORE variety in strikes. Not the chopslicechopslice we have now. Obsidian helped with this in NV, using special skill moves and such.
Situational Melee kills in VATS:
As an example:
You're in VATS, and a super mutant is right next to you, and you are holding a hunting rifle. Instead of pressing the normal "VATS action" button, you use a different button, such as X on XBOX or Square on PS,This would have your character hit the mutant in the butt of the rifle, rather than shooting them. This would have multiple effects of varying magnitude, depending on different factors, such as Strength, Guns, and Melee Weapons. These effects could be: Crippling a limb, Damage (Which would vary, but be a constant) as well as knocking the target down (depending on strength.)
Another example: You're in VATS, and you're in a house, near a wall. A raider in in close proximity to you. You are unarmed. You press the button (Previously mentioned). Your character takes the raider's head, and slams it into the wall. depending on your character's strength and unarmed, this causes a varied amount of damage, as well as: A crippled head, unconciousness (Lots of fatigue damage), or a complete head explosion in true Fallout style.
Mostly those two, but feel free to comment on it and post your own. (that is the point of the topic, after all.)