Is the nexus the right option for my needs?

First off, thanks for your time.

I am thinking about buying the nexus media player now that it is only . My other option was getting a rasberry pi.

My main goal is I want to use it for emulators to play old roms. There are plenty of good emulators in the play store and I can just sideload them. I would also like it to have plex which I know it does.

If I go with the Raspberry pi I can just load retropi on it but I'm not sure if I can then use plex.

Lastly is the controller- http://forum.xda-developers.com/nexu...llers-t2973028
That convenient thread lists potential options.
I already have a wii u pro controller. I googled to see if it is compatible and did not find any clear answers. Do you guys have any experience with this or know If I can just buy a bluetooth dongle and usb adapter to get it to work? Will this dongle work on the raspberry pi?

If this doesnt work I can always get the 16 dollar Nyko Play Pad Pro that it supposed to work with this

Overall which option do you guys think is the cheapest/most convenient for me?
Is there another system out there that I am not thinking about that would be an even better option?

Thanks again