I am due to upgrade soon, and I currently have a 4s. I am looking for more information on both.
I have iPhone 4s from work and Samsung Galaxy Note 2 as personal phone.
Only reason to still carry iPhone is for corporate Exchange email, other than that it is useless to me.
Android/Note 2 advantages:
More flexible configuration, bigger screen, Torque Pro (not available on iOS due to the Bluetooth constraints imposed by Apple). Did I mention reliable navigation?
I could find many free applications for every need I have. I can set up default application for every action (like play music or messaging or web browsing).
I do not flash custom ROMs, but I like the fact that I have the choice if I want to.