I don't like the idea of school uniforms. If a family is too poor to afford clothes, there are programs (at least in my state) to assist in that. Kids can actually get some very good, and fashionable, clothes even with that assistance.
My issue with uniforms is that they really don't serve a real purpose. If kids are going to be jerks to each other, they'll do it despite uniforms. That crosses out that "reason" for them, at least for me. I think students should be able to wear what they want- within a reasonable dress code. Allowing students to choose their own clothing within a dress code may also be good practice for when they enter the "real world" and must dress themselves appropriately for work (if no uniform is needed then).