Selfhosted

as always, the answer is "it depends" - everyone has their own unique flavor of *arr stack with different components. Breaking it down, everything revolves around the core apps:

• Radarr, for movies
• Sonarr, for TV shows / anime
• Lidarr, for music
• Readarr (now Bookshelf), for books/audiobooks
• Whisparr, for porn

These apps do the majority of the hard work of going from eg. "I want this movie" to "this movie file is now downloaded and placed into a subdirectory on my NAS or storage somewhere"

Realistically, all you need to get started is a download client (usenet, torrent client, whatever - the most popular choice is qbittorrent-nox or an equivalent docker container), your *arr app(s) of choice, and a way to consume and share the media you've now downloaded to your NAS or server (plex, jellyfin, stash, audiobookshelf, VLC, etc)

For consuming media, here's a non-comprehensive list that most people will recommend at least one thing from:

• Plex or Jellyfin for audiovisual media. TV shows, anime, movies, porn, audiobooks, and music
• Stash for porn-specific media, if you prefer. Significantly better metadata handling and management designed specifically and only for porn
• Audiobookshelf specifically for books and audiobooks. Again, better metadata handling and management designed specifically for books/audiobooks
• VLC or an equivalent if you prefer mounting your media share to your PC and just playing the raw files

The rest of the *arr ecosystem serves as a way to automate this core idea or fix issues with that automation. An example from my own homelab:

• I have every *arr app listed as the core for finding/downloading whatever media
  • I have two instances of Sonarr and Bookshelf. One Sonarr for TV shows and one for anime, and similarly one Bookshelf for regular books and one for audiobooks. the way data management is handled in these apps it's significantly easier to set up two instances of each rather than trying to force everything into one app
• I use Prowlarr as an indexer manager. You can add indexers to each app but it's easier to set up Prowlarr and let it do the handling and search caching
• I use qBittorerent for the actual downloading and Plex for sharing. I've found that friends and family have a much easier time both finding and using Plex, so I stuck with that over Jellyfin
• I set up Unpackerr because often times you'll find imports for the *arr apps fail because they're compressed in some way. This just automates the finding and decompressing of those files so they can import successfully without needing me to go in and do things myself
• I use configarr to automate the application of the TRaSH guides to each *arr which significantly increases the odds of getting a good quality version of whatever it is you're looking for when doing an automatic search
• I have Seerr set up so friends and family can request movies, TV, or anime on their own without needing to message me all the time
• The *arr apps do an okay-ish job of constantly looking for upgrades for existing media but they fail in a lot of unexpected ways so I used to run Huntarr. After that imploded I created and now run Fetcharr. If a better version of something I have is ever released it'll nab it automatically
• Since I'm a filthy dub watcher (I just can't do subtitles, sorry) I have Taggarr to tag anime series as "not the dubbed version" which works well enough
• I just set up dispatcharr for live TV which was a fun little side-project and maybe could be useful later. This was one of those "ooh pretty" set-it-up-and-see-how-it-goes things.
• Because automated requests from Seerr and Fetcharr can clog up your queues with failed downloads pretty quickly (stalled, bad releases or naming, etc), I set up Cleanuparr to deal with that whole mess. Works pretty well, no need to check and clear things myself any more
• My wife can't do any media without subtitles so I also have Bazarr running to download those for any media that's missing them
• I also set up Maintainerr because I've realized my friends and family have a habit of requesting stuff and then never watching it, so this prevents media from completely filling up the NAS. It deletes media based on rulesets. Mine is customized to delete unwatched stuff after X days
• I also have Mixarr set up which I have mixed (hah) feelings on. Just takes my music I listen to and grabs artists I don't already have. Very obviously vibe-coded which makes me nervous because of the type of people who vibe-code popular apps and the thick skin required to publish popular apps to the internet. So far I haven't found anything better
• I also recently set up audiobookshelf for books and audiobooks. The metadata handling and management is ehh so I may look into LazyLibrarian to clean up and properly tag downloaded media before audiobookshelf pulls it so it can actually get the correct books and authors
• I also have Stash running for an interface to Whisparr, since adding porn to Plex would be a terrible idea. My friends have kids and they watch a lot on the Plex. It would be super unfortunate to have porn as a recommended video
• Finally, I run tautulli for stats upon stats upon stats. And because Mintainerr can make use of it
• FileFlows and Tdarr are also popular for compression, health checks, etc of existing media. I ran them previously but don't any longer

Not all of these will be useful to you, and you'll likely find others that are more useful for your situation. Like I mentioned, everyone's *arr stack is different and unique.

My recommendation: start with an *arr or two, configarr (optional but really recommended - hard to set up but once you do you're good forever), prowlarr (optional but you'll thank yourself later if you ever get into this and end up with more *arrs), and unpackerr (really do recommend this one) and go from there.