Sedu hair straightener vs CHI?

I bought the sedu hair starightener about 10 years ago and now it works liek crap. It barely straightens my ahir and makes it all frizzy. It is the old version of the Sedu. I really want a new straightener so i started looking them up and found the CHI straightener, which one do you recommend. My hair is frizzy, thick and curly. I need a AMAZING, GOOD straightener.