Plastic back and a removable/user replaceable battery.
Yeah yeah I know it "feels cheap" but honestly I LIKED when phones were made of more plastic. Now they're heavier and both sides are breakable. Like, the metal backs were fine, but apparently metal backs suck for NFC and wireless charging so instead of giving us some classy Nokia Lumia style plastic they went with glass backs.
Also I keep my phone in a case because otherwise the back is so smooth it shoots off the couch if someone walks across my apartment. It's legit only in the case to add some friction.
Every time I try to do this I burn my onions.
In I'm sure TOTALLY unrelated news I'm also getting screened for ADHD...