Love p90x. Because I get bored working out, and feel like I can get a really good lift in a very quick period of time.
I'm not at all impressed with the cardio on p90x. I wish there was a better balance. Felt Kempo was worthless. Plyo is pretty tough, but not nearly what you can get if you can blend in Insanity on the off days.
Ideally... p90x / Insanity hybrid is a nice routine for a person that wants a good mix between weights and cardio.