I went through public school from K-8, then attended a private high school for 9-12. The private school had a uniform of slacks (kahki, navy, or olive), button-up dress shirt (blue, white, yellow, or pink, ha right pink), a belt, any appropriate neck tie, dress shoes, and a navy blazer for 2 quarters of the year. The public schools were wear what you want.
After experiencing both, I would take the uniform over anything. Period. About 6th-7th grade when you suddenly become self-conciscous of your image and the opposite sex, you start spending more and more time refining your image. I'm almost embarrased how much time I spent combing my hair, figuring out which shirts to wear, and what shoes were cool to impress some girl I got no where with.
Uniforms were great, no need to worry about what you wear. I just threw the clothes I needed in an althetic bag with no worries about what matched what, what looked cool, and on occasion, what was even clean. I wore the same tie for probably 2 years without changing it. Just threw it in my locker at the end of the day. It seemed strict, and it was, but I'm comfortable in dress clothes and if tie tieing were an Olympic sport, I'd be in Athens. In high school there is so much to worry about, it was a huge relief to have one thing that was carefree.
And actually, uniforms are much cheaper than buying designer clothes and t-shirts that cost 40 bucks. I think I only needed a few pairs of pants, a few shirts, and even though I got a dozen ties every christmas, I only wore one