Been doing CrossFit for about 2 years. I'm 65 years old and I've always been fit, because of running, biking, going to the gym, flexibility training, etc. But I can honestly say that I've never been is as good shape as I am now. When I play with other guys in my age group they marvel at my flexibility and my swing speed. I highly recommend it.
I haven't tried Insanity or P90X. They both look like very productive routines But I do agree that Cross Fit is great workout! It's the most productive workout protocol that I've used in over 30 years of working out. And as a previous poster said, the workouts are scaled to your own individual fitness level.