Wear school uniforms and Students to decide what to wear to school. Which is better??

Wearing school uniforms and or students to deciding what to wear to school - which is better?

When I was a student in middle school, I should had to wear school uniform, but when I was a high school student, high school didn't have any there was no school uniform. If students want to wear a special or beautiful clothes, it is a good for students to decide what to wear. And Also, because juveniles (the word teenagers can be used in place of juveniles, but this is not grammatically incorrect) grow up faster, students they don't need to buy the same uniform a few times if students they don't wear school uniforms. In spite of those advantages, I prefer to wear school uniforms - these are the reasons why I think so; 
First, if students have school uniforms, they don't need to waste time choosing clothes in the busy rush of the morning. Because of that, they don't worry about being late. If they prepare their school uniform and make sure that it is clean, that's there's no problem.
Second, if students wear school uniforms, whether students are rich or not, it is difficult for people to distinguish the difference. Poor students don't care worry about that problem.
Third, school uniforms are a symbol of the school. When students behave out of school , students they try to show some manners to other people. That is, so it is possible for students who have school uniform to control their behavior even though they decided to do something bad. 

Therefore, when students wear the same clothes, though they maybe be not characteristic distinctive (I think this is what you're trying to say, if not, I apologise!), they focus on studying - they don't need to worry about not being rich, they can be careful to do something (unsure of what you mean here, sorry!). Because of those these things, I prefer wearing school uniforms.

[Great opinions, very good text. Well done!]

Wearing school uniforms or  students deciding what to wear to school. Which is better??

When I was a student in middle school, I was supposed to wear school uniform. But when I was a high school student, high school didn't have any school uniform. If students want to wear a special or beautiful clothes, it is good for students to decide what to wear. Also, because juveniles grow up faster, students don't need to buy the same uniform a few times if students don't wear school uniforms. In spite of those advantages, I prefer to wear school uniforms. There are reasons why I think so.
First, if students have school uniforms, they don't need to waste time choosing clothes in the busy morning. Because of that, they don't worry about being late. If they prepare and clean their school uniform, that's no problem.
Second, if students wear school uniforms, it is difficult for people to distinguish whether they are rich or poor. Poor students don't care about that problem.
Third, school uniforms are symbol of the school. When students behave out of school , students try to show some manners to other people. That is, it is possible for students who have school uniform to control their behavior even though they decided to do something bad.

Therefore, when students wear same clothes, though they maybe are not characteristic, they focus on studying and they don't need to worry about not being rich, they can be careful to do something. Because of those things, I prefer wearing school uniforms.

[Very good.]