The thing with the Moto G (even the very first model from September 2013) is that with essentially vanilla Android, with no heavy customisation or bloatware, the phone has always been nimble.
Having added 2GB of RAM now, an even faster CPU, plus a Sony 13-megapixel image sensor, you can really begin to wonder what you're getting extra when paying £500-600 instead of £160-200 (8GB/16GB model, each with a memory card slot that will happily take a 32, 64, 128 or 200GB card).
Sure, the LG G4 and Galaxy S6 have better cameras, but for someone taking photos to share? 13MP is ample, as long as it can work in all lighting conditions. And a dual-tone LED flash is a boon for getting the light balance correct.
I have a load of phones at my disposal, but I've always respected the Moto G and recommended it to loads of people. Often people buy something more expensive and powerful because they simply don't believe the Moto G can possibly be any good. They're convinced it will lag, yet in so many tests a vanilla Android device will usually have a smoother user interface than any customised stuff from Samsung, LG or HTC.
TouchWiz on Samsung phones seems to cause untold problems. You have an eight core phone, and it stutters when doing simple things!