I have owned both a iphone 5 and a s4, went from being a apple fan until I got my hands on the s4, my main reasons for preferring the s4 are the fact the os is opensource and updated nightly, opensource means the os code is open and available to the public to read/write as they feel fit making custom os available (roms), also the fact about using your phone as a mobile harddrive that's exactly what I do plug the phone into pc and a chunk of my sd storage is available as mass storage same as a usb flash, not to mention all the other features on the s4 that may or may not be useful, eg the magnometer used to alert the phone when a phone case covers the screen the nature of android os being open source allows developers to use this hardware as they feel fit (for example a metal detector) useless I know but you would never see apple allowing anyone to view edit there source code let alone use the phones hardware