Tourmaline, Ceramic, or Titanium?

I am not new here, but haven't posted in ages. I am looking to buy a flat iron for my daughter. Her hair is thick naturally curly and she generally has it done professionally. I want to start doing her hair myself. She does wear it natural sometimes and already has some heat damage from years before.

The information online I have found, doesn't seem to be very helpful, there are so many conflicting ideas, so it's hard to tell.

Any advice would be great!