You might want to consider the MiniX
Basically, its a high end android tablet connected to your TV with built in XBMC.
Works well with 4K TVs, runs KitKat so any android app will run on it. Will prolly be a little overkill for simply "playing around with" but it can function like a very good HTPC to stream all your UDH/FHD vids from your pc/nas.
MINIX NEO X8-H - MINIX