Why does it always have to be "The Best"? Most people would benefit from at least doing something, no matter what. All this obsession with finding the best causes a lot of people to do nothing instead.
Interval training has always been a cheat-code for me in terms of getting in shape, then staying in shape when I wasn't able to spend a lot of time in the gym. As someone who comes from an engineering background, I have a special appreciation for how efficient it is in terms of time-spent and results.
Small study shows exercise is good for everyone, people continue eating fried yogurt for breakfast, doctors shrug and continue prescribing cholesterol-lowering pills because they make more money on office visits and lab tests.