I am currently using my XBox 360 via WiFi with the XBox app of Windows Media Center connecting to my computers Windows 7 Media Center that has all the movies, pictures and music on my NAS drive. I would like to mimic something close to this on my children's bedroom and my bedroom, as I have put a lot of their movies onto MKV, AVI, XViD, and some other that I don't remember right now (am always looking for the best compression with the best viewing quality and sound) so they can watch it on our TV and not have to grab the original DVD/BD as my 9yr/5Yr have scratched bunch of them fighting over which one to watch or taking them out and leaving them out, and they'll fall to the tile and get stepped on or whatever.
I can, of course, purchase 2 expensive XBox 360 and do the same thing or get me some kind of media player streaming device. That's were I need your help. I have been reading about Roku, Roku 2, WD Media Player, Sony (whatever name), etc. As I have read, it seems as if the WD seems to be one of the best. I really could care less if I can stream from online YouTube or anything else, since I would rather have movies that I have in my NAS more than anything, plus that gives me piece of mind that my kids are not watching something that they shouldn't.
Any help would be greatly appreciated it as I don't want to go to my local CompUSA and purchase/return several items.
Pros/Cons of each equipment would be great. H264 seems to be the compression that is used the most. Some movies are MKV 3D, so maybe a future 3D device would be cool for such bedrooms as the LG 55" LED 3D that I already own is the reason why some movies are 3D.
It's not released yet, but I would expect the best available tool would be the Ceton Echo over a Coaxial MoCA network connection. To be honest, I'm not familiar with any of the other devices you listed.