I'm sure for everyone when considering making a new purchase there are many variables that come into play. Design form, audio quality, and ease of use all contribute to my personal decisions when choosing what product to purchase for new audio equipment. I find the benefit of around-ear cushions more comfortable and offer a heightened level of audio playback during use in comparison to using earbuds. Over-ear headphones also offer noise reduction and canceling, both from the passive function of the physical barrier from the cushion and additionally our noise-cancellation technology found within headphones such as the QuietComfort 35 II headphones. Naturally, this has the drawback of size and portability - larger devices are not necessarily as convenient to travel with, in comparison to a device that can fit in your pocket.
As a personal purchase, this question will vary between everyone based on their unique needs from the system. I'd love to hear everyone else's contributions and thoughts from the Community too.