I think removing the legislation limiting who can sell coverage where would be the best. Keep the marketplace, even. The real savings would be me being able to deal with more than just two companies in shopping for coverage. If that became 20 companies, prices would obvsly drop.
Also, there needs to be legislation/regulation focusing on what costs are covered, which service, and by who prior to receiving services. There have been multiple times where a doctor tells my fam that my insurance will cover certain components of their services(this is after they have supposedly made contact with my insurance co) then months after the service, I get a big ass bill noting portions weren't covered. This is the stupidest industry in the world when it comes to trying to actually get a cost prior to getting the service. That needs to be regulated because the market has done everything it can to make sure it isn't clear and transparent. This is a really good example of where regulation is needed in a market that doesn't sort itself out.