100% Overhauls/QoS:
I've said it before and I'll say it again, a believable
traffic system,
NPC behaviour (this can be interpreted broadly, from their walking patterns to their reaction when something explodes) and
police system are the three most important things things the game should improve upon.
Three main things to improve? Now that's not much you might say, but it will take a lot of work and I'm not optimistic even one of those things will evolve into something believable.
After that fixing
player shadows and the
water would be nice.
You might think i'm overly critical, but you don't stay engaged with a game for that long if you don't like it
ps: I don't get why some people still want 3rd person, it was announced OOS (out of scope) at least a year before release