Just my two cents, don't buy the iPhone 5c.
As much as it pains me to use the word futureproof, if you are one of those people who likes to hold onto their device for a while - the 5s is as good a starting point as any.
And then via Twitter:
I just spent the past week doing the best I can to understand Apple's A7 SoC. In short? It's insanely fast. http://t.co/AgWzGv1ljr