Most B&M and Vekoma flying coasters. I just don't trust the way they're built. Everytime I'm in the downward facing position, I always feel like the weight of the cars is gonna break off of the track. The only flying coaster I really did enjoy was Soarin' Eagle at Luna Park, and that was built by Zamperala. But the reason why I enjoyed that one more was because I thought the weight of the cars felt a bit more in balance, and you're laying on the cars rather than above or below them.