The two reasons I picked the G4 over the S6: external storage and replaceable battery. However with quick charge and qi charge (via a sticker or replacement back) I've never actually had to replace my G4's battery in the field, so the S7 is in the running this year, now that Samsung have brought back the microSD card.
Lack of wireless charging is why no other phone was considered last year, and why the G5 is probably never going to grace my belt pouch...