Should I upgrade to the iPhone 4S or the iPhone 5?

I'm eligible for an upgrade on April 2013 or I could upgrade earlier on January 2013 but it would come with an early upgrade fee which would be $180.00.

I currently have the iPhone 4 and I'm not sure whether I should upgrade to the 4S or the 5 for a few reasons such as -

I fear that the iPhone 5 would be hard to use with one hand whereas with the iPhone 4S I would easily be able to use it with one hand as the 4 and the 4S are the same size.

If I get the 4S I would have iOS 5 on the phone which I prefer to iOS 6 because iOS 5 has Google Maps, Default Youtube App.

Also, design wise I don't know if its just me but I think that the iPhone 4S may have a nicer design than the iPhone 5 I liked the steel band it has around the phone and it looks nicer with the glass front and back as opposed to the aluminum back of the iPhone 5 with two different shades of black.

So should I upgrade to the iPhone 4S or the iPhone 5? Or what I could do is not use my upgrade and get the iPhone 4S for $200.00 if I trade in my iPhone 4 to this cell phone place near my house which does trades for phones and i'd be getting a refurbished iPhone 4S that is in near mint condition.

Or I could just stick with the iPhone 4 and wait and see what the next iPhone is like other then using up my upgrade on the 5 and not being able to upgrade to the next iPhone after the 5.

What do you guys think? What is the best choice to make here?

Good things come to those who wait