I bought a 128GB iPhone 7 because that's the lowest amount of storage you can get with jet black. Otherwise, I would have gone for 32GB. I wanted to be able to store all of my music, which is less than 13GB, and all the apps I need. I can regularly delete pictures and videos after uploading them to Google Photos, so I'm not worried about them taking up a lot of space, and I use Hangouts for texting, which only keeps recent messages stored on my phone until I decide to scroll to older texts, so I don't have to worry about years worth of pictures and videos hogging up space on my phone (I never delete texts). I had so much space left over that I also downloaded my entire Google Play Movies collection, which consists of five seasons of Game of Thrones and nine movies, that I'll probably never watch on my phone, and several 1-2GB games that I'll probably never play, and I still have 74GB available.
32GB would have been plenty for me.