Usenet pros:

• not p2p so no real chance of getting busted
• max out your bandwidth the whole time you’re downloading
• no need to seed, no ratios, etc
• Cheap AF

Usenet cons:

• Files aren’t forever. Servers do delete content after some time so search results aren’t always available on your server
• Usenet servers, especially in the US, are pretty responsive to DMCA demands
• Not free
• Complexity of setup (Sab + Arrs) are a barrier to entry
• Public nzb search engines aren’t always going to have what you need. Private search engines are usually invite only and/or cost money per year
• Far less variety for niche stuff than torrents (imo, ymmv)

Quality and ease. Torrents don’t always have enough seeders or they disconnect. You can get by on them, but it’s a case of getting what you pay for. I go through a lot of media as do my friends using my server. The cost is negligible and basically means I have no headaches.