Over-The-Ear Headphones or In-Ear Monitors?

For the first 15 years of my DJ career, I always used conventional over-the-ear headphones.

When I started producing music around 5 years ago, a friend of mine suggested that I try in-ear monitors. It took some time to get used to them, but since then, I have only used in-ear monitors for both DJing and music production.