I like the idea of not having "uniform" (ie expensive logoed stuff) but having a dress code, like at work. So, proper trousers, shorts or skirts(no denim, lycra, tracksuits), a real shirt or blouse in a light colour, option of a tie, and a suit jacket, blazer or pullover. Younger kids (ie under 7) could have plain dark tracksuit bottoms, plain light polo shirt and a cardigan or jumper.
Proper shoes, no logos or slogans on bags or coats. No high heels, no daft hairdos, long hair tied back, no jewellery. Tights to be opaque, socks below the knee and black/white. Sixth form to be allowed sober makeup and maybe stud earrings.
Would be nice to have no rules, but I remember school- IME it was the kids from poorer backgrounds who made a big deal about logos etc - the kids from the new estate had nice m+s smart coats, it was the poorer kids covered in stripes and logos.