Neither is necessarily better overall—it's just that one is likely better for your specific hair type. “Ceramic plates are the safest because they suit dry, damaged, or fragile hair,” Abramite says. “Ceramic plates have negative ions which help retain moisture, add shine, and prevent frizz for a smooth, shiny cuticle.” The overall temperature of ceramic irons stays in a relatively safe range with even heat distribution to prevent hot spots that can cause damage.
Meanwhile, titanium plates heat up very quickly and can reach higher temperatures than ceramic irons. In a Cosmo article about silk presses, hairstylist Kerry Joly says titanium flat irons are ideal for getting an extra-smooth finish on natural hair. Regardless of the flat iron you choose, keep the heat at the lowest and safest temperature possible to still straighten your hair and use a good heat-protectant spray beforehand.