Headphone jack, if the fair phone 5 still doesn't have a headphone jack, fairphone demonstrates that their user hostile company. Removing the headphone jack while introducing earbuds was removing customer choice to force people to buy earbuds.
I don't care how repairable the phone is, if it's designed to remove optionality from me. I'd rather have a phone that gives me more options and is less repairable, then a phone that's very repairable but not user friendly.
Hell, they're all about replaceable, user serviceable modules. Make the headphone jack an optional module!