Best flat iron for thick hair?

I want a new flat iron, mines over 5 years old. I have a Bio Ionic, and it worked great, it's just worn. I have heard great things about CHI's, but I don't know if they're more commercial than anything. Any reviews on Sultra? I have really coarse, thick hair, but it only has a slight wave to it. I want one that is healthy for my hair, will provide shine, and will make it look thinner. I have a $150 ish price limit. Thanks!