It doesn't depend on hair type at all. Because my hair dresser recommends a thick one for my hair but I use a thin one because they get to the roots better. But the new thing I do is the night before I straighten my hair then in the morning I take my Mini Pro and just do my roots and my hair gets super straight.
I think it depends on how you use it, not your hair type. I used to use a thick one & now I use a thin one. I figured out there really isn't much of a difference, the thicker/wider ones get the job done quicker, but the thin ones you can use for several different styles & make wonderful curls.
I have a thin one & my friend has a thick one. We have used each other's before, and I must say, hers straightens our hair a lot better than mine does. They are the exact same brand and everything. Just different thickness. We both have thick hair also.
It depends on your hair type. for me i have long and thick hair so a thick straightener works best for me. my sister on the other hand has short and thin hair and the thin straightener works best for her. it all depends on your hair type.
Depends on your hair, usually thick works good on all