Yaata SMS - Nice customisable sms app, small size.
MiXplorer - Solid file manager, but not currently on the play store.
Facebook Messenger Lite - Stripped down version. works great with no battery drain. easiest to find on
APKmirror. If facebook do add adverts into the main messenger app then this will become a necessity.
Monospace - A minimal notes and writing app.
Shuttle+ Music Player - A solid no nonsense player. Got it free through the amazon store.
Flixster - Current film releases & reviews from rotten tomatoes(if you like rotten tomatoes)
Boost - For reddit
Signal - as a Whatsapp alternative.
#Squaredroid - add borders to images without it cropping into the photo.
PocketCast - for Podcasts. perfect interface and feature set.
Nova Launcher - Because its Nova and its great.
Google Wallpapers - Wallpapers that change every 24 hours. Is actually surprisingly decent!
Simple Currency - for very simple and clean currency comparison.
Sleep - Smart alarm clock with sleep cycle tracking