Honestly for what you’re trying to accomplish, any PC built in the past 10 years would suffice.
I’d say the bigger issue would be what server operating system you’d want to run. Personally I use UnRaid and I love it, all of the apps you mention and more are available as premade docker templates in the Community Apps plugin. I’ve tried Windows and FreeNas before but I find UnRaid just so user friendly and reliable.