I’ve just ordered a Shuttle XS36V501 barebone with a 8G DIMM and 120G SSD. That model is made for 24/7 use with advertisement walls etc, handles quite high and low temperatures, is tested with Linux and is fanless.
My research has lead to this brand and model but I have not heard very much about it. Most people seem to use ordinary PCs or Raspberry equivalents leaving a gap between these two. Hopefully my purchase will fill this gap and give enough performance to satisfy my house automation needs while being energy efficient and long lasting.
I will report more as I go.