Apps I or my family would need to seriously consider WP as a replacement to our Android phones:
Snapchat
Dish Anywhere
SiriusXM
Amazon Music
Pinterest
Runkeeper
Google Apps (Hangouts, Gmail, Maps, YouTube, Voice)
USPS
FedEx
Apps I want updated
Synology DS apps, particularily the DS Photo+, to add in background upload. I think WP8.1 has an API for background picture backups they could tie into.