U want more function like dual windows and better social integration but can accept some lag and a hard to handle screen, take G3.
If you want pure android with smooth and lagfree interface and fastest android update but with lower speaker vume, lower contrast screen but brighter, take n5.
In my opinion, both has almost same battery life in my usage for 2-3 months on each phone.
And you be surprised the camera is better on the n5 and probably best in android space, when I compared to big names like Sony z2 and m8.
Many reviews has bashed n5 for its lousy camera and battery life. But for me, these 2 are fine for me and in fact same or better than most flagships.