The advantage of private trackers is that:

• torrents almost always have seeds
• you can ask for re-seeds in case they aren’t
• torrents have a good quality
• you’re less likely to receive a complaint letter from copyright holders

There are some niche private trackers which have an active community that handle quality and requests. Also they don’t let just anyone create a torrent, so you can have assurances that the files have been vetted to some extent and you’re not going to download something unexpected.