I prefer american shchool clothes. They are more individual and we can enjoy changing a fashion everyday. ^^
When I was highschool student, I didn't like school uniform. (especially our school's) It was all navy blue (dark), long skirt and we always had to wear school badge at uniforms. It wasn't cool! :( We always tried to shorten a skirt about on the knee or more shorter and dye hairs and some of my friends got another school's uniforms (better than our school's :P) and they changed to another uniforms after school every day.. Ah, and when I was highschool student, "loose socks" was really the fad. (boom) I wore them everyday. :)
I think some Japanese girl school uniforms are cute! And some guys look cool in the blazer type uniforms. But to wear the same uniform for 3 or in some cases 6 years must be boring. It is fun for young people to express themselves through fashion!!