Personally iOS 8 and the new ability to auto delete messages history after 30 days and the coming iCloud photo library allowed me to comfortably go back to a 16 GB phone. I had a 32 GB 5S, but as someone who streams all my music and video on the phone I no longer need anything more than 16 GB with these new features that allow me to more efficiently use the storage on my iPhone.
Depending on how much space you use on your current phone, I'd consider trying out the 16 GB and seeing if it works for you. It seems like people have trended to buying significantly larger storage on their phones than they need (people who can't fill 64 GB deciding they have to have 128 GB because it exists, etc.).
I can't seem to decide what to do. I'm very impatient and only 17. I really want a 64gb iphone 6 plus but Target currently has only 16GB. What should I do. It's sold out everywhere and my online purchase says Oct21-28