So many different opinions, so I might as well weigh in.

I’m a classic story of starting with a 1TB external HDD to now my 160TB server. I just kept going and didn’t know when to stop. It’s very affordable to make sure your server is extensible. Start with a decent case with lots of HDD bays. A Fractal R6 is excellent. A modern Intel CPU does great transcoding for x265 and AV1. No GPU required. Then you just need 8-16GB RAM (more is better, but it’s expensive right now). Maybe 256GB SSD (more is better, but it’s expensive right now). Get one HDD right now. Whatever has a good price/TB. They’re also expensive right now.

The more important question is the OS. I actually prefer Windows. It’s free (if you look on Google how to activate it for free). If you get more than one HDD you should consider DrivePool to pool your drives. Works great and cheap one time cost. If it’s data you can just download again you don’t need to worry about backup. RAID is a good intermediary step, and for that SnapRAID works really well. You’ll need one HDD for parity, and a good rule of thumb is no more than 5-6 HDDs per parity. RAID means that if a disk dies, you can restore the data. Much cheaper than cloud storage.

This is what I use and it’s great. Low power, cooler, quieter, and in the current economy, MUCH cheaper.

Spoiler: I am deeply into the arr “ecosystem” and love the shit out of it.

I think I finally understand Linux fans. Yes it’s confusing for new people, but because I’m so into the weeds on this stuff I love how much choice I have. And if one of the projects doesn’t have what we want, someone makes a fork.

To point: you really only need Sonarr and Radarr. Get those set up and working how you like. I recommend the Trash Guides. Once that’s working how you like, get Prowlarr for easy management of your usenet and torrent indexers. Most people should stop there.