First there was the Boxee, then WD Live, and now Mede8er. You won't find anything better unless you build your own. (Rasberry Pi / NUC).
Apple TV, Amazon's stuff, Roku, nVidia Shield. They all have there place, but for playing locally stored movies, none will do what the Mede8er can do without a bunch of issues, third-party software and a ton of tweaking.
The biggest thing for me is the ability to support DTS HD-Master & Dolby TrueHD and the ease of just being able to turn it on, press play and watch a movie without any problems is where the Mede8er shines.
If I didn't care about that, I'd be playing everything with my ATV. Come to think of it, I could save a ton of space by removing the hd audio from all my files...Nah, forget that!