Straightener suggestions?

Okay so this is my hair type, it's thin, straight at the top, a little wavy on the bottom. I have a straightener but it dosent reduce any frizz. I have that at the top. Whenever i use my sisters straightener, a chi, my hair has like no frizz. I don't want to get the same straightener as hers, so is there any that you can recommend to me? Btw I would prefer a thin plated straightener.