I just switched last week from the G4. The 5x screen is not as good and it feels less premium in the hand but I'm pretty happy with the 5x. I will be keeping it for 2 reasons. First it is lighter than the G4 but the best thing for me is the fingerprint scanner
. It works great and I love that I can take the phone from my pocket and unlock it in one swift motion. Hope this helps.
If you prefer a bigger screen G4. If you prefer more features and control with the camera, G4. If you like a fingerprint scanner, 5X, if you prefer pure android, 5X. If you're into rooting and custom roms, 5X.