Fact: Dad's love practical, well-made technology!
You dad is probably satisfied with the earbuds that come with his iPhone. However, if you really want to upgrade his listening experience (and style), you need to buy him some PowerBeats3 Wireless. They wrap around your dad's ever-expanding ears so they don't fall off when he's moving quickly (as he can). They connect easily to computers, smartphones, etc. and sound great. If they are good enough for Apple and Dr. Dre, then they should be good enough for Dad.