Why? I have an s6 and I have a hard time believing there is a better device anywhere. Not a hater by any means but you say g4 all the way so I wanna hear all about this beast.
Both devices definitely appeal to different preferences. Just because one side has strong feelings doesn't mean we should resort to labels or my dog is better than your dog.
One side likes the G4 with a nice large display and camera. They need the card slot and ability to swap a larger battery trading off premium materials for plastic back covers with hyper glazed finishes or leather.They realize that they need to buy an accessory for wireless charging. They are fine without rapid charging, fingerprint scanner, dual wireless charging built in, dual mobile payment, and less energy efficient but comparable chipset. They do have 5.1.1 out of the box and firmware updates should improve things a bit.
The central question is the G4 compelling enough to switch. For me and some others, the answer is no. Hopefully, with 5.1.1, those affected by cell standby and battery drain, etc., a great device will be even better. We are also looking forward to Samsung Pay with tap n go and MST. Some of us aren't so much spec conscious, believe it or not, and with more energy efficient hardware and matching optimized firmware, a smaller battery can do the job of a larger one. We don't miss the card slot and swappable battery and appreciate the inclusion of above missing features in the G4. We prefer a smaller device and love how super thin, fast and smooth it is.