Don't fall for the private tracker meme.
The concept of bittorrent, just sharing cool stuff from my computer to yours, is long lost.
There is no real usermade interesting soykaf on it, not even just some cool stuff someone found. It's just an index of seedboxes filled with media ripped from a few sites by scripts. Maybe someone uploads an rip of an old CD he found somewhere, but some greedy fuck's seedbox immediately grabs it.
There is no real spirit of sharing. You can't seed back to anyone, because of the seedboxes, you are not motivated to share, and by the time the 2 week hit&run period expires you can't wait to delete it from your torrent client, because why should you share it, it's up on someone's seedbox.
But on public trackers, when you find some obscure soykaf, with one single peer, that's active for 2 hours a day, it feels so good when you see that you can share that back to other people, and you know that without you they wouldn't've been able to get the files they wanted.
The closest thing to just simple sharing is Soulseek. You can share folders, and others can browse your folders, and download files they like. There are some people with really huge collections of music and lots of other stuff.