I went to public schools for K-12. I got very lucky with my K-6 teachers, I think. My 7th-8th grade education was pretty good, although who knows because puberty was a very distracting experience.
In 9th-12th grade, I focused more on non academic development and in retrospect I think that turned out to be a good thing? I think school overall focuses too much on knowledge, and not enough on social skills and values. That's just my gut sense though - maybe I'd feel differently if I had gone to a different school. Overall I feel good about things though.
Are you happy with your K-12 education?