I have very thick, curly/wavy hair. As a little kid I had big, loopy ringlets which have now turned to coarse, frizzy waves/kinks. My hair can't be styled without first being straightened, so I use my flatiron religiously.
I have used a CHI for the past 3-4 years and to be honest I feel that CHI is a bit overrated. I have enjoyed my CHI while I have had it, but I have realized there are cheaper brands out there that can actually do a better job. It might be partially because I've had it for so long and it's wearing out, but I feel that my CHI does not get sufficiently hot (mine has gold plates and no adjustable heat settings.)
Recently I have tried out a Remington (I'm not sure of the name but it's about 1" with blue plates) and I love it! It does a bunch better job than my CHI and makes the hair much flatter. It can be set all the way up to 435 degrees but 410 is enough for my hair. The Remington is also relatively cheap compared to brand like GHD and CHI so it's surprising that it works so well.
I have only had a GHD used on me once quite awhile ago, and I actually don't remember what the results were like. I would love to try this brand again because I've heard from lots of girls that it's the best but it's soooo expensive.
For now I am loving the Remington and planning to get my own soon!