from this perspective use cardio to build endurance and strengthen the heart
don't use it to lose body fat. cardio DOES NOT burn fat, it burns calories.. not the same thing
diet adjustments are what burn fat.
i know this might not be what you want to hear but it needs to be said because i see the same people doing cardio over and over everyday at my gym and they are still fat. it is not working! it is what you do in the kitchen, not the gym that causes fat loss
as far as my own cardio. i like swimming and jogging.. i also do gymnastics which is great 'cardio'.