Real answer: I have had or experienced medical care in England, Spain, and the US. Despite horror stories I saw no difference and the English medical care at an Emergency room was far faster and got directly to the solution rather than using referrals. They tried to get me to stay overnight and I kind of got out of that but I now feel (having later had to spend a significant stay in a very new American hospital and realizing the English one was just as clean and new-looking) that perhaps I had been scared by propaganda. Spain was completely free clinic even though the patient (not me) was a visiting tourist and was also really fast and friendly. But that was not a major medical emergency.
In England there certainly are complaints about the Dental system. The NHS is not paying enough and dentists can get out of serving NHS patients so there is either huge lines or you pay a lot. I did not experience it so I can't say first-hand, but this is the one area where I believe the US system is superior. There was some other posts here pointing out that how Dental works here with users actually able to and having a motive to do price comparisons may be an explanation. I also know first-hand (being across from the USC Dental School) that poor are served by these for free, though I am unsure if this is enough to make up for the lack of an NHS-style government program to serve them.
I am unsure how that could be applied to major medical however: if your deduction is $3000 then you don't care if the hospital is going to charge $10000 or $50000, that's a good deal different from comparing a $50 or $100 cleaning. Maybe it could apply to doctor's visits but then people just don't go at all if it is not free, while they will get their teeth cleaned because it is an obvious service, not just somebody looking at you.
By far the worst place I ever saw was when I was a kid and went with my father to an emergency room in Vegas. We went to the public hospital and it was a kafka scene, pretty horrible. After hours we finally saw somebody, who realized my father had insurance and said we were at the wrong hospital, and sent us to the really nice and clean and completely empty private one where he was treated within 30 minutes of arrival (it was a fractured ankle). This is before Reagan signed the law that said all emergency rooms must treat all incoming patients. I think it is interesting that this has not turned all emergency rooms into this scene, instead the ones I have been to since seem to be as nice as that empty private one was.