I would love to suggest the HA green but as it only has a non swappable eMMC flash storage (and I ha a former HA install that killed a eMMC) I would rather suggest something like a Odrois M1S which is essentially the same hardware but with more extensive storage options and double the flash for around half the price. The bucks you save can be reinvested into a nabu casa membership to support HA!
Downside of the M1S at the moment is that their is no HaOS available for it (but it should be actually trivial for the devs support it in the future).