The nexus 5 is a decent phone which comes with android lollipop which is the latest android version these days, if are are a android lover then you must go for the nexus 5 as it has some great specifications such as:-
4.95 inch hd display
13 mp camera
android lollipop
and other great features
the main thing is that it is a smarphone made by the company google hence the software version will not be updated as soon the update arrives .