I am looking to buy the pedal that will allow me the most creatively when editing to come up with completely new sounds.
Of the pedals you mention, that's the Boss GT-8 or -10 AFAIC. The 10 is theoretically better and I like some of the features on paper, but I haven't spent any time with it.
To be honest, the king of this kind of things is Native Instruments Guitar Rig. I'm a terminal tweaker and nothing else has anywhere near the power and flexibility of Guitar Rig and a decent laptop. When I got GR, I immediately sold off my POD Pro and my GT-Pro as even together, they were hopelessly outclassed by GR.