>I have yet to see the metropolis that checks all of those boxes, or any of them for the matter.
I hate beating this drum because it's borderline stereotypical at this point, but Tokyo really should be studied because for an incredibly dense city of nearly 14 million people they manage to achieve quiet, safety, cleanliness, privacy, and affordability
>I want quiet
Visit the residential neighborhoods of the largest city in the world, Tokyo, and discover that you can get quiet with density. These are not mutually exclusive items, we as American society have somehow decided that noise pollution was an acceptable feature of urban landscapes. Japan decided, as a society, that anti-social noise activities in residential areas were bad and makes sure it stays that way.
>safety
A controversial topic pre-loaded with mountains of baggage, but IMO this is a result of policy and philosophical decisions. Japanese cities are incredibly safe at all times of the day -- you can leave a phone out in the open and no one will steal it. A lot of theories as to why that is, but the end result is clear: Japan, a city of 14million residents, is safe.
>cleanliness
Interestingly enough, 1960s and 70s Tokyo was a bit infamous for its litter/trash problem. I am a little fuzzy on how they turned that around, but they did and today it's one of the cleanest cities in the world. Again, a societal decision that has enforcement with teeth. And mind you, there aren't a lot of trash cans on the street. You have to carry around your trash with you if you generate any until you find a suitable trashcan or take it home with you. Yet the streets stay really clean.
>privacy
I will hand it to you, a big city can be a lot less private. But there are ways to create that sense of privacy within a more dense urban residential area without sacrificing density. Also, as density rises, you can get a weird counter-intuitive effect where the crowd affords you even greater privacy.
>affordability
The average house in Japan costs around $400,000 to build from scratch. Yes. You heard me right. When you buy a house in Japan you buy the lot it sits on, demolish the previous house, and build a house customized to your liking (designed and built by one of many competing housing companies). All for around $400,000.
Now, is it smaller than the current average American 2-story house? Yes. Is such a house size necessary? As it turns out, that's also a philosophical question and society over there has decided that in a trade off between smaller house + more urban density vs bigger house + less density, the density was worth the trade. You can definitely spend a million dollars and get yourself a proper sized mansion. But at least you get a proper sized mansion.
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This isn't direct at you specifically, but one thing that frustrates me in the debates between urbanization vs non-urbanization in the USA is the lack of imagination everyone possess. So much possibility, so much possibility that IS ALREADY PROVEN and yet we circle back around the same things. American cities aren't the only way cities are. Our cities can be so much better, they HAVE been better, and we can make them better again if we collectively as a society choose to.