If you're happy with OpenBSD, probably any computer is good enough
The problem with arguments like these is to me two-fold:1. Physical space. Most of the older tech takes too much space. I don't live in a mansion and I have no dedicated rooms just for big bulky computers.2. Power consumption, heat, noise. I would love to be less consumerist and use stuff from 15 years ago and stop feeding greedy corporations but... the old stuff consumes 90 to 200 watts, heats up easily and noticeably, and can get loud.Both parts of this problem are trivially solved by modern tech. I got a 13" Chinese fanless laptop second hand for 160 euro; it has a Celeron J CPU with 12GB RAM and 256GB SATA SSD. It can do anything I need that's not programming or rendering -- including playing 60FPS video -- and last time I checked it, it consumed 30W under full load (all CPU cores at 100%) and idled at 11W or so.Modern tech is not only about its buyers being mindless consumerist drones. It offers tangible benefits, including long-term environmental sustainability.Yes a lot of CO2 was likely released due to its production but I'd wager that tech that heats up less and uses less power can last 10-13 years and will pay off its environmental footprint with a generous interest on top.So unless you're a retro collector or want to write compilers for older CPUs, there are zero reasons to be excited about older computers.(That being said, if somebody finally creates a modern 6502 CPU computer e.g. in the shape of a 10" netbook I'll buy it immediately, provided I can also program it through USB from my workstation.)