I'd give them a cheap Android phone that lets them play games and browse Youtube, and maybe one with a good camera so they can take pictures. I wouldn't give them iPhones because giving expensive stuff when they're still young would make them think they deserve having expensive things without working for it.
Yeah they are insanely overpriced for nothing...But I guess most people actually giving phones to their kids or have many in one family gets those deals that lets you pay per month for the phone and whatever subscription type you have.
And yea as for actually giving them a phone, I'd just give them some old thing with buttons if they are not too old so they can call and text you know.