Advice before buying my first "pro" camera

I'm a college student, a fairly successful filmmaker, and I've finally saved up enough money to buy a semi-pro camera. I'm stuck on what to get? I'm looking at the Canon C100, Red Mysterium X, or the Black Magic Ursa Mini (not out yet).

I currently shoot on a Nikon D750 with a 14mm, 28mm, and a 70-200 2.8.

Any advice would be appreciated!