It almost certainly has to be Hearn.
He has the Sky contract, he's a genuine boxing enthusiast and has the wider financial and administrative resources of his father's Sports Network empire which is profitable and professional. It is also noticeable that Hearn has yet to have had a major falling-out with any of his fighters; always a good sign.
Mick H and Frank W next - their businesses are built around boxing, they have smaller but still creditable broadcasting outlets, both men are experienced and genuinely know the business.
Things then begin to look rather thin with Frank Maloney, the Hattons and Hayemaker all in the running but not really in a position to make you a TV star or stadium filler.