I love all three of them, too. In fact, when I am not in a rotation (doing Xtrain) they were my 3 main "go to" workouts. They are all tough and advanced. Personally of the 3, I think CF is the most fun and TTM the toughest. TTM and CF also have a lot more options via premixes than AB. However, AB is low impact, so if I want an intense workout, but I just did a lot of plyo the day before, I always go to AB. They are all awesome workouts. In fact, I am a month into Xtrain and I am working all 3 into the rotation for the next month. I miss them!
Edit--btw, you mentioned how you like HIIT, tabatacise and step, well you will get all 3 of those in TTM. Plus metabolic weight training (like in AB). So TTM gives you a ton of variety all packed into one intense workout. And like I said, the premixes are awesome so you break it down to any length you want.