I have tested a lot of bags and there are a couple that stands out.
the easiest to find is the ones in current production ofcourse and that is the Wilson 15-pack. A really really nice bag with extremely good compartments and small pockets. Only downside is the straps are at the wrong side of the bag, making them dirty when playing on clay.
Headīs old Djokovic monstercombi is semi-easy to find and that is the largest i have tested.
Babolats aero 12 pack is nowhere near those 2 bags. I currently have one Aero 12 pack 2013 and its really good quality and all but the bag interior is not close in size to the above 2 bags