pcDuino3 Nano.
A20 (1Ghz ARM CPU), 1GB RAM, 1Gb NIC, HDMI, MicroSD, SATA, USB,
5V 2A power, Arduino shield pinouts.I don't recall this being mentioned in this group before, but it's supposed to have been available for a few months for $39. It doesn't seem to be widely available in the UK yet -- there's plenty of the earlier
So like the Banana Pi, it should make an acceptably good NAS, with its SATA port and 1Gb NIC. With limited support (in the English-speaking world, at least), there's again going to be a question about the stability of the distros (compared to the huge support for Raspbian).
That Arduino-shield compatibility is a definite plus. But as with other A20 boards, I expect that if it's going to be placed in a case, then a finned heatsink would be needed, and a large hole cut in the case for it.