T-Mobile. If you are a legal video or audio streaming provider and you meet T-mobiles technical requirements, you can get zero rating. Everyone is on a level playing field.
Verizon and AT&Ts zero rating of their own services: there are four national carriers and a few regional carriers with their own networks. There is plenty of competition in the wireless space.
Cable companies zero rating their own content on their own network: Technically, all internet providers have peering arrangements where if they have more outbound traffic than inbound traffic, they make up the difference with payments. Since it is there own traffic, they don't have to pay another network provider. Of course, realistically, the cable companies are doing it to be anticompetitive.
The real answer is make it easier for there to be multiple companies to provide Internet access in a given area. they would start competing on price, speed, data limits, etc.
Luckily, I live in area where I can choose between Comcast's crappy service and AT&Ts gigibat internet service - no data caps and a flat $70 a month.