I still believe Cathe reached new heights with the her Ripped with HIIT series. I love those workouts, especially the Lower Body Hiit circuit and the Upper Body Hiit circuit. They are just about perfect in my estimation.
I'd love to see a sequel.
Oh yeah....RwH is one of the best series. It's the most recent gem in my opinion. Lower body circuit is taxing with those plyos but they whip legs into shape. It's pure fun! Oh did I quote it's ADVANCED?