What do you mean "largest"? If you mean girthiest, I'd say a Blood python, but they're about the same length as a Ball. If you mean next longest, yikes, I can think of a number of species off the top of my head that are longer, without getting into the giants.
Water pythons, jungle carpets, coastal carpets, olive pythons, amythistine, Savus, Macklotts, womas, black-headed. they're all longer, but not considered giants, except maybe olives, they get kinda big.