I am with Dr. Mark Chapman at Mt. Sinai, but he is a little older, so if you think someone younger might be better, Dr. James Marion is great- anyone really is fabulous: they have an entire amazing IBD center there with doctors, nutritionists, surgeons if you need them, etc (ranked #5 best GI center in the country after of course Mayo, Cleveland Clinic, etc.: https://www.mountsinai.org/ibd-center