More cars
More guns
Being able to bring stuff to your safe house
Better friend system
Being able to buy new phones
hair cuts and more clothes
customizing cars
More melee weapons
Better fire system
Being able to shoot out a windshield
Ability to break NPCs arms,legs,etc.
Possible to learn more fighting moves
Buying places to cut up/sell drugs (you stand on a corner long enough and people can pull up and ask for drugs,you can hit a button to give it to them or not,it could be a cop,a stick up man,or a rival gang member that will shoot at you)
This is my biggest one here Bring BACK THE EMPIRE MODE FROM GTA:VCS