I have some experience with this since I went straight from high school to working in San Francisco. I don't know about the best city for someone without degree, but the best city for tech by far is San Francisco. To give you an idea of how dense the tech scene is in SF, the headquarters of Uber, Square, and Twitter, are all within two blocks of each other. There are hundreds, if not thousands, of other tech companies just a few blocks further from there.
As for companies, I have found it much easier to interview at larger companies than smaller ones. When I applied to three larger companies (Uber, Google, Dropbox) all of who were interviewed me and eventually made me an offer. I also applied to six smaller companies, of which four rejected me without interview, and the remaining two wound up making me offers.
Since I was unsure whether I would be able to get a job or not, I deferred from college for a year, so I could always go back if I couldn't find a job. Depending on your situation, this may or may not apply to you.
As for companies, I have found it much easier to interview at larger companies than smaller ones. When I applied to three larger companies (Uber, Google, Dropbox) all of who were interviewed me and eventually made me an offer. I also applied to six smaller companies, of which four rejected me without interview, and the remaining two wound up making me offers.
Since I was unsure whether I would be able to get a job or not, I deferred from college for a year, so I could always go back if I couldn't find a job. Depending on your situation, this may or may not apply to you.