My current favorite is ZCY (X30 and X32). They are basically Intel BayTrails. You just need to remember that BayTrails have this funny feature where they would not boot off the GPT partition, so you need to make sure your boot devices are MBRs.

Just got another X32 for a different project. I replace broadcoms with Atheros and use little VESA mounts mounts from Ebay that I drill into a dry wall by the ceiling. After that mounting them on a wall is no different than attaching them to the backs of the monitors.

I recommend AliExpress as the source for the systems themselves ( blows ebay out of the water ). Strangely, mounts are cheaper on Ebay.