Hmmm.. 4S is now $99, and the 4 is free on contract.
A few months ago I would've said - see what u get for free with Android (mostly crap or formerly high end phones being discontinued).
Now,Verizon has a Galaxy 'stellar' with a dual core 1.2ghz and 4" display for free along with the iPhone 4, and the obligatory 2 crappy Androids (single core old tech, 320x480 etc).
The stellar isn't bad, but it's not a clear winner vs iPhone 4. 4G LTE, 4" 800x 480, 1.2Ghz dual core, all looks good. Then u see the 3.2 MP camera... Vs iPhone 4 3G, retina, and an excellent 5MP camera, not to mention the resale value is way high when u upgrade later. Then there's battery life - a sore spot for most Android phones.
At best it's kind of a toss up now.
But compare $199 Android phones to the iPhone 5. And one thing that free Android phones have that even the $100 4S doesn't have is 4G.