Actually, I'd recommend all of them. (I'm always good at spending other people's money! }(
Beans is totally right: Cardio Kicks takes up a lot of floor space if you do it strictly as produced. However, with any travelling moves, you can substitute a lot of in-place moves, from the moderate (calf-pumps, for example) to the insane (ice breakers, power hops, knee-smashes with knee lift, front kicks and side kicks, etc.).
Cardio Kicks
CTX Kickbox (awesome ab routine on that one as well)
Kick Punch and Crunch (another awesome ab routine on this one)
Boot Camp (which has some to-die-for kickboxing sequences)
A-Jock