I am very shocked that people are/were having such issues with their GNex's. This is a developer site as much as it is anything. Have you tried other ROM's? I have the standard battery in my GNex and can get about 10 hours of regular (for me) use on it. This equates to about 1 hour screen on time (email, web, candy crush, adam carolla, calendar...). Currently running Slim ROM - 4.3 with lean kernel. I do have an extra battery in my bag but have only needed it a handful of times.
That said, I was just in to look at the G2 and also the Note 3. I found the Note 3 just a bit too big for my liking. I would have walked out with the G2 had it not been for the stupid lady at the V store. She asked why I didn't want it and I told her I would take it in a second as long as she could keep me in my unlimited plan. I told her I was sold a bill of goods from Verizon when I signed up. They kept telling me that with the 4G network I could do anything I wanted, and if I got the unlimited plan I wouldn't have to worry about any overages. Well, a few short years later and they are making you pay extra if you want to keep it (bait and switch!!). Typically I use between 6-8Gig/mo., I travel a lot and stream videos, music and podcasts. Changing plans I would end up paying about $75/mo more to get me to that same level. Sorry, got off on a rant there.