<< They're all good, and you should alternate through them. Search for "HIIT" in the advanced forum search and you'll find a quick and easy workout that will wear your ass out and help you start dropping pounds. >>
This system really works, it changed my cardio workouts completely (and cut the time i spend on cardio in half), i usually do it in the morning, before i eat or after training, before i eat to make sure i am burning ketones and not glycogen...
Patrick