Other than the control to choose map, i feel the most important thing to change is to limit the map control that both defenders and attackers get even before the round starts; there is no fight for map control, defenders can completely shut down a site and attackers don't have to worry about a flank with a perfect cypher/jk setup.
imo the map control should be limited to spawn so that player will engage in early battles and have to use abilities for the same.
p.s. pardon me for bad englando.