My children went to a school with no uniform (primary).
Maybe it is different at secondary, but from my experience,
There was no bullying about clothes - nobody particularly cared about what anyone else was wearing (though they did tend to wear broadly similar clothes - jeans/leggings/joggers, t shirt, hoody, trainers - nothing innapropriate)
There were no arguments the night before or in the morning over what to wear - DC just got up and put some clothes on, just like they did during the school holidays.
I never experienced any pressure from DC about particular clothes.
I saved money because DC just wore their normal clothes (particularly on shoes, because I didn't have to buy impractical "school" shoes).
I didn't have to faff around making sure uniform was laundered at the weekend, they just wore whatever was clean from the wardrobe.
DC tended to be more comfortable, because they could dress for the weather.
If you ever lost clothes, they would be returned promptly because everyone would recognise them.