Intel’s line of mini PCs have worked well for me. They call them the Next Unit of Computing, or NUC.

Older generations [of the hardware!] have more stable Linux support. I currently have a gen 4 Intel NUC (Haswell) and it is a lovely platform.

Not a lot of local compute power though. For that, it seems better to go all-in on well cooled datacentre hardware and connect to it remotely.