be interested in details of the bird ID app if you woul d not mind? ive got a 4 iPhone and it does all that I need , simple if you want it to be, more complex as your knowledge and needs grow.
I've got an iphone 4s after much debate on here, and to say i'm happy is an understatment , I can easily move money from my buisness to personal accounts ,surf the net ,messaging is so much easier now i'm used to it , dates notes and reminders make my life easier, everything is better than a basic mobile , it's a nice looking bit of kit ,so nice to hold , tactile's the word i think ,oh and a decent camera and screen to see what i'm taking pics of . If I had to go back technology wise to a non smart phone It'd be like swapping a colour tv to black and white.
I've had all the iPhones from 3G onward and currently have the 5. The 3GS was a great bit if kit in its day and is still quite functional now. However, this is almost certainly the last new version of the iOS it will run so you'll be handicapping yourself a little for the future if you opted for that one. My advice would be a 4S which is a nice bit of kit, is dependable and very easy to use indeed. Much less fiddling around and less bugs than an Android phone. Just my 2 penn'orth!