The private sector has less transparency, representation, and accountability in how it conducts its affairs. Through the state, we’d have at least minimal representation and a requirement for public record-keeping. Also, it’s a lot easier to raise premiums than to raise taxes. The public sector is a tightwad and will only allow so many expenditures, thereby preventing the widespread problem of over-treatment. I’m not completely sure if I’m on board with single-payer, (I have some kinks to work out, e.g. whether or not abortions would be funded), but it’s the best alternative I can think of.
That said, I would consider a push to separate insurance coverage from employers and just place it on the open market, provided there was a social safety net for those who couldn’t afford it. I don’t see as strong of an organized movement for such an endeavor, however.
I’d frankly take either option over what we have now.