owning both i would argue wether the s4 camera is actually better. the n5 is also better built (a big one for me coming from 'solid' iphones and is faster.
on another note i should be getting my s4 back from repair tommorow... what rom would people recommend ?
build quality I'd give you, camera I think is a dead heat once you've put a new ROM on it, the standard TW cam is fantastic but once you lose the samsung side it becomes average to good.
Speed I personally think is either something I'm completely ignorant to which I find hard to believe, or its a perception thing. I've got an iPhone 5, a Moto X and an S4 and I honestly can't tell the difference between any of them.