Pornhub VR ;)
No, seriously: WhatsApp (every day), Navigon, Play Music (own music library, no subscription), Alarm Clock (every morning), Browser, Steam Authentificator (also for chatting with my Steam friends), calender, GMail, camera app
Youtube and other streaming stuff only when I have WLAN, I try to keep my mobile traffic low.
Always running in the background: PayPal (instant notification of any money transfer), eBay (when I'm buying or selling something), weather app
Currently playing on my Z5 Compact: Chameleon Run (one of the best endless runners, very cheap in the current Humble Mobile Bundle), The Room Three, Rayman Adventures. If I connect my DualShock 4 via GameClip: GTA VC & LCS.
Currently playing on my iPad Air: Deponia, Severed & The Whispered World.
