Hardest Pilates teachers in NYC?

I know this was posted a year ago but I figured instructors come and go so wanted to ask who people think are the hardest Pilates instructors in NYC? I've liked all the teachers I've had, Erin Ginn especially, but am still fairly new to Pilates so I am curious whose classes I should try? I did a class with Itsy for the first time that was the most intense I've done and very fun.