Better or be good and different than GTA 6, what APB definitely has over GTA 5 is character customization and that is part of what makes it great. Another thing I think APB does better than GTA is PVP, GTA 5 is definitely more of a coop-pve game than pvp (not to say it doesn't have its pvp modes.
But APB probably wont reach a level of triple A, comparing APB to other titles it definitely sits at indie level.