7 inch would totally do for this (maybe something along the lines of a Teclast P71) - I have a TF101 for serious tablet use but sadly the Tegra 2 just sucks at video decoding. Cheap as less than 150USD. preferably less than 100 but that seems impossible right now. Plus points if there is Cyanogenmod for it, but if the stock image works, I can do without that.
I am aware that the battery is not going to like being attached to power all the time all that much, but then again it does not really matter. I just felt that going for a unit with screen would allow music playing without turning on the projector it is going to be hooked to (those lamps do not particularly like running all day
As for remote, there is always upnplay on my phone / TF101 to control the thing :P.
The WD units are decent but you cannot install your own apps for what I know. On the other hand, for Android the main thing I am wondering about if there is actually a decent Android HTPC application out there.... If so, any 1080p capable Android platform with HDMI could do the job, really, even something like https://www.dealextreme.com/p/1080p-ful ... cal-101713
I mean ideally I'd want xbmc but that means I have to buy a 250USD+ PC to run it on (for some reason my current Nvidia based mainboard in the NAS just cannot run 1080p very well under Linux even though the chipset has hardware acceleration for it)...