Whatever is cheapest.
Honestly there's really nothing in it App or performance-wise or in the general experience of the OSs. Anyone who tells you different merely has a pseudo-religious devotion to an electronic device. And why would you listen to anyone who worships a phone, or a phone OS? It's as bad as worshiping a console...
Personally I'm an ABA (Anything But Apple) because of the cult of Apple. But if the cult of Apple doesn't leave a bad taste in your mouth then the iPhone is a very good device, just like all the other high end smartphones.
What do you do when you have a genuinely objective choice between high quality devices? You make a cost-benefit analysis and go with the one that comes out best on that. I don't know anything about 4 (or 3.9)G LTE so that could be quite a big deal and could make all the difference in terms of choice. But iPhone 5 isn't the only 4G LTE phone available, so why has the choice come down to a 4G iPhone and a non-4G Nexus?
“The fundamental cause of the trouble is that in the modern world the stupid are cocksure while the intelligent are full of doubt.” - Bertrand Russell
"When the power of love overcomes the love of power, the world will know peace."
Jimi Hendrix
