http://www.huffingtonpost.com/2014/12/22/16gb-iphone-6_n_6367188.html?utm_hp_ref=technology I have to ask. What are you people doing with your phone that 16GB isn't enough? I have a 16GB Android and don't need more space. My prior 32GB iPhone was never even close to filled and that's the reason I just go a 16GB phone this time.
I use 9gb on my windows phone, but I know my girlfriend almost filled up her 64gb 4s with photos and apps she never deletes. So to answer your question, photos and apps.
I would never have a 16GB iPhone because after installing my apps, that would leave me with barely 6GB left. Add in very little music and then some pictures, and you are out of space. I also have a 16GB Nexus 4 but the storage space on that has been enough for the past two years but that's because I never use it for pictures because I have an iPhone and Googles music player sucks compared to the music app on my iPhone.
I have a 6/64GB and mine is mostly music. Very few apps. I would use a 16 if I streamed my music, but for the cost of only $100, what the hell, why not have the 64GB. I also like having the space should I need it for taking videos or lots of photos.
I'm only using 9.3GB out of my 64GB at the moment. I think it has a lot to do with the cache a lot of apps keep too.
Bah humbug. 8GB is just fine. For my mother-in-law only, of course. She upgraded from a flip phone, and doesn't have a computer. -t