One of the most valuable pros of a flat iron is the ability to straighten any hair type. It fits best curly, thick and difficult to style hair. But it's a little more harmful to thin one. I usually recommend hot straightening brushes for weak hair. A brush straightener uses a lower temperature than a flat iron, so it doesn’t damage hair so much. For this reason, it's not recommended to use flat irons on a daily base. Hot brushes, on the contrary, can be used daily. A lower heat temperature and the ionization function of an electric brush allows to use it every day. But there is a recommendation - give your hair a rest for a few days once or twice a month. Your hair will be thankful to you.
Also if you want to lose some volume it's better to style hair with straightening iron. Flat irons make hair very smooth and hair loses volume. Special bristles of a hot brush save hair volume vice versa.
Another advantage of a straightening brush is a speed. An electric brush straightens curls several times faster than a flat iron. It gives perfectly straight hair as quickly as combing it.
And as for me, hot brushes are easier to use. I suppose a child can deal with it. Finally, it's more likely to burn yourself with a flat iron. Electric brushes have special attributes to protect your fingers and scalp from accidental burns.

Read more about straightening brushes and flat irons here: https://mystraightener.com/