I've got the 2/16 GB model of the G3, and I personally love it. After upgrading to firmware 10J from 10F, I saw a huge improvement in battery performance and drainage. For me it lasts an extra few hours after getting some basic settings tweaked like turning off NFC/Bluetooth, and having WiFi disabled when it's not in use. Also another thing to do is to stop WiFi from searching for other networks automatically.
So far with this setup, I'm getting through a full day and well into the night till I put it back on charge. I have battery saver to enable once it hits 10 percent. I'm going to check out DS Battery Saver tomorrow and try that for a week as apparently it gives about another hour from what I've read.
My usage tends to be all the social sites, FB, Gram, Snap, etc pretty much throughout the day with a few hours of Youtube at night and lots of picture taking.
I wouldn't go back to the G2, OP. Tweak your G3, disable a few things and wait for the new firmware release.
LG G3 16GB D855 • Stock Android 4.4.2 V10J Rom • Stock Kernel • Purple Drake • G3 Tweak Box