Which straightner works best ghd, chi or sedu?

i'm 13 and i have medium to long normal black hair. i've only straightened my hair once for a party, and i loved how it looked. i'm from asian descent so my hair is usually straight, but since i'm growing out my layers, my hair has become very wavy but only the black part of my hair. the front part is slightly wavy, but its more like around the bottom part of my hair. PLEASE ANSWER IF YOU'VE HAD EXPERIENCE WITH AT LEAST TWO OF THEM, and please name what kind (like a chi nano and a sedu pro-ionic). and STAY ON THE TOPIC. i DON'T want to hear stupid stuff about whether ionic or cermaic are better. also please give me an honest review, dont just say chi. or i'll get really mad because people like those piss me off..