Of course the U.S. has the chicken-and-egg problem, but public transit is my vote if I could wave a magic wand. I am tired of car cities: more pollution, obesity, rage, and sprawl.
I'd say the logical place to start in the US is by finding the streets that have negative cash flow just from maintaining the infrastructure, and start handing those streets back over to the home- and business-owners located on them, in whatever way seems the least politically suicidal. If you live in a cheap SFH on a whole acre,or own storage units, there's no reason you should expect urban-quality roads, water, sewage, and emergency services.
I agree, and it seems like many people share our feelings, which makes sense when you look at how the most desirable cities according to our views are getting more and more expensive. Of course there aren't many of these cities in the US.
The solution I'd love to see is giving these cities more competition. Let's try to revitalize old cities like Baltimore and Cleveland to give people more affordable options. I've heard Pittsburg is having some success with this kind of thing.