I love this community, I used to rant about efficiency all the the time on reddits self hosting community and everyone thought I was insane. If the damn thing is going to run 24/7 for 5+ years then put a little thought into its power usage!

I personally love old Dell optiplex micros on eBay. Cheap, plentiful laptop hardware in a cute little box which allows modest upgrades. My primary server in a full sized case is just a laptop CPU, Ryzen 5600g. It brings me joy that my network has four servers and still is under 75w idle for everything including networking gear.