Something small and 2 or 4 GB RAM. Raspberry pi’s compute power is good enough for me, I’m not doing anything too intensive.
Is raspberry pi 4 still the best answer?
I am a tinkerer and don’t mind tinkering. I typically use Gentoo Linux as main OS. I also don’t mind ARM or other architectures. I’ve been eyeing the RockPro64 as well.
I recently wrote a blog post about the new NAS I built myself and why I didn’t choose for a RPI 4. https://jeroenpelgrims.com/diy-nas/
I think it terms of price it won’t be much more expensive than an RPI NAS, but you’ll get more performance and stability.
If you don’t care about power usage and/or connecting stuff through USB you can also buy some older hardware instead.