I had a couple of Acer Aspire Revo boxes (the NUCs of their day); one running Windows for media streaming and NAS, and the other Ubuntu for a development server plus Postfix/Dovecot for email. Come replacement time, I found NUCs and dedicated NAS boxes were too expensive for what they offered. I ended up building a PC with low power components, battery-backed RAID arrays and 32GB of memory. It runs Vmware ESXi which boots from a USB stick. Infinitely more flexible than bare-metal, with enough power to cope with anything I need it for. It gets left on 24/7 and draws about 60 watts on idle.