Hi Allison,
I think Kick Punch and Crunch is more challenging cardiovascular wise than Kick Max.
Kick Punch and Crunch also features a stability ball ab routine that is great.
On the other hand, Kick Max has intermediate level drills, but it really kicks up to being very demanding during the Blast Challenge!
Also, Kick Max has some great Leg Conditioning Drills that help tone the legs and enhance form for kicks.
If it were me, I would buy Kick Max due to the very demanding challenge and the leg conditioning drills.
I think Kick, Punch, and Crunch and Kick Max compliment one another.
Cheers!
Amy