I use Paperless-ng and it’s great. Headlining feature is that it stores your documents in PDF in a plain folder which makes backing up easy. Another software that puts your documents in a database is no good unless it has its own backup method.
Plus being on a network server means I can set up my printer to scan to there as a target, my phone to scan to there, computer, I can drop emails in the consume folder, etc. Easy peasy to get stuff in there.