Personally, I would prefer a system with some government agency responsible for negotiating drug and medicine prices with the manufacturers and using their superior bargaining position to get much better deals. Then, I would set up a company with a Fannie Mae type status to offer affordable plans (which shouldn't be too hard since the costs of medicine, which is like 90% or more of costs would be negotiated down and bought in bulk). Private insurers would have to lower costs by a lot more or just go bankrupt. Let the market work amirite
The government will save money from this, so I'd also add in some money-throwing at medical infrastructure R&D.
Since Medicare would cost less, I'd turn it into a system that pays for all costs, along with expanding it to cover new mothers and kids under 16.