I would say use both. Right now i train with very high intensity cardio 5 days a week for 45 minutes, Heart rate about 175 bpm. Then I lift in a separate work out and do 20 minutes of low intensity cardio after that. I seem to maintain muscle well as long as my carb intake is on point and i do alot of compound movements. Lots of Power Snatches, Power clings, Deads, Squats, Rows etc..........I lost 60 pounds in 5 months on this type of program and was in the best shape of my life