The cable chop sounds great on paper, but when it comes to the execution it's less of a core exercise and more of an arm blaster. Also, the resistance changes drastically from beginning to end.

With this method, the Swiss ball acts as a cam similar to what you'd find on a machine, giving you the feel of constant, equal tension throughout the ROM and putting that tension right where you need it.

Related:  Big, Thick, Chunky Ab Training

Related:  Hit the Deep Core Muscles