Your hair is a frame for your face. In the terms of beauty, it depends on what shape your face is as to what hair style looks the best.
Plus it's a very personable question as everyone has different tastes.
My suggestion is that you wear your hair as it naturally falls. Rather than damaging it with various chemicals, colors, and essentially setting it on fire with straight irons, just allow it to have it's natural look and find somebody who likes it that way. Otherwise you'll be asking what wig to wear when you're 30 because all your hair has been destroyed from the abuse you put it through.
I like straight hair mostly, but it depends, if you are black for example then curly hair looks nicer than artificially-straightened hair. Normally maybe shoulder length but quite short cuts can look sooo sexy if done right like Frankie Sandford for example link
but please don't shave the sides of your hair or anything like that it looks awful