I have a LG G3 (love it!) I traded in my nexus 5 for it (which I love too). Both great phones. Nexus 5 is fast with a clean Ui, decent camera at best, nice screen and size. Very comfortable to hold and always running the most up to date OS.
LG G3's screen resolution and size are amazing! The Ui is a little or a lot intrusive (my last 2 years have been straight Android experience) but in a good way because is full of LG's features that are just going to make your life easier: knock code, messaging window, Qslide. You can customize the Android main keys.
Very impressive camera, fastest shooter I've tried and many many other things that I love. My only problem... Is not stock Android... And even though LG's UI is not as bad as Samsung s or HTC s it is still a skin on top OF VANILLA ANDROID and it's gonna lag from time to time.
I'm also waiting for a Nexus 6, not because I need but because I want it and I'm pretty sure that the nexus 6 won't have much, if anything, over the g3.
I know I didn't answer your question but I thought sharing my experience could help you make a decision