I always wanted 1 thing in GTA.
I want to be able to choose jobs. Like a cop (just driving around surveying or responding to random 911 calls), firefighter (random mission of car fires, buildings on fire, rescuing a cat etc.), pilot (airline, touring, police support, coastguard etc) , bodyguard/security (defending vips, FBI stuff, and looking cool with sunglasses) with more dept then just the old 12 lvl mission that where to linear and simple.
And maybe a mix of realism and over the top stuff from San Andreas.