Besides the necessities (google apps, swiftkey, etc..), I'd say the app that served me best through all those years is smooth calendar. I had this app since my first android phone and it has always been on my homescreen.
Nova Launcher
Viber
Pandora
Boat or Dolphin Browser
DroidTV Primetime
Type Mail
SwiftKey
Xfinity TV Go
Android News By Pinenuts Developers
Google Maps (Navigation)
Evernote
ES File Explorer
Ultimate Backup Pro
Google Drive
Box
ChompSMS or Google Messaging
Es file explorer
Press RSS reader
Yelp
Tip and split pro
Google maps
One drive
Tapatalk
Bacon reader pro
Android wear
Package buddy pro
Amazon app
Couple (to talk with the Misses)