Let's say I haul out my CD's I never got rid of over the past 30 years and my DVD's from the 2000's. I can still legally rip them, right?

If I took those ripped copies and wanted to stream them, what would be the best platform to do that?

Jellyfin if you want free, open source, and don't need special clients (like for LG TVs, Xbox, etc). Emby paid if you need the clients.

Skip Plex entirely. Their users are their product. They've partnered with media companies and push partner services over users media library. They like to claim that Plex Media Server doesn't send any information back to them, and its technically true; its the Plex clients that are sending the data back.

Plex