As a stylist, I have used a lot of flat irons/hair straighteners, including Sedu, Hai, Infrashine, Chi, Paul Mitchell, Solia, Big Sexy, Andis, Babyliss Ghd, T3, Kenta etc. You should get a Professional hair straightener, they style much better and faster, and most importantly, they protect your hair.
In terms of performance:
The best ones are: Sedu, Kenta, Solia, Infrashine, Ghd. These are top of the line professional brands
Above average: Chi, Hai, Paul Mitchell,
Average: T3, Big Sexy, Andis, Babyliss
Below Average: Conair, Vidal Sassoon, Revlon, Bed Head etc. These are cheap consumer brands that you will find in drugstore. If you care about your hair, do NOT buy them.
Helpful Flat Iron Instruction Video:
How to Curl Hair With Straightener
How to Use a Flat Iron
How to Add Volume to Your Hair:
How to Create Sexy Waves with a Flat Iron
How to Flip your Hair:
=== Tips for buying professional hair appliances ===
Do NOT buy professional hair appliances from unauthorized places like amazom.com, eBay, Target, Walmart, etc. Because if you do, manufacturers will refuse to honor the warranty. Buy from licensed places like salon, licensed professional beauty stores like Folica.com, Ulta.com, West Coast Beauty Supply Inc. etc