So I've had my Nexus 4 and 7 for well over a year.
The 4 has always had a weird problem where once in awhile the battery would drain unusually fast. I upgraded to Kitkat about a month ago and the battery life got much worse and the phone would unlock even with a pin code while in. Y pocket and change settings, usually with the time and set some timers just as it would do if I had the slide to unlock set. After three hours off the charger with minimal use, the battery would sometimes be down to 70% and sometimes! down to 40% after 7 hrs. When 4.3 was released, I upgraded and that seems to have fixed the battery life that the first two Kitkat releases gave me and of course the dialer screen is fixed.
When I bought the Nexus 7, I was pretty much happy with it and the after a few months, started hating the developers for not making many of my favorite apps in a tablet version. So it's been a year and four months of owning it and some of my apps that I have installed now have tablet versions and some of them are pretty impressive now and comparable to the versions I have on my iPad. I have one app that I am very happy with on my Nexus 4 and iPhone but it has not been updated for my iPad since January. Not sure what the developers problem is there.
Also on the Nexus 7, I could never get over three hours screen time between charges. Switching from AT&T to T-Mobile did help and that's something that I noticed on my iOS devices as well. I always got worse battery life on AT&T and Verizon then on T-Mobile.
Between my two iPads (Retina Mini and Air) and my 5S and the Nexus 4 and 7, the battery life on the iOS devices has always been impressive and sorely lacking on the Nexus devices. Sounds like battery performance is still an issue on many Android devices still today. At my job, everyone with a non iPhone is always plugging in. When I do use my iPhone during a night at work, it's still at 95-97% after 7 hours.
I've been wanting to get an S5 but I will most likely get the next iPhone and then wait to see what Google does for the next Nexus if there is one.
Currently I use the Nexus 4 at my job in case it gets stolen, I can live without it. It would bother me much more to lose my iPhone.