Field is a big big dude with a very good trainer in Jesse Reed but he didn't impressed me at all till now. Tyson Fury is a guy with limited talent but lot of charisma, hence why he's a bit more known than what he should, a kind of John Duddy HW version. I think Tua is still the one with the biggest chances among these 4 from what I've seen but I must admit I don't know much about Mo Harris so I can just go by what I've seen.