It depends on what you are seeking.
For software, warez sites are usually better than torrent sites. It is important to note though that this is probably only because on warez sites, there is very little fear of repercussions for sharing malicious content. On top tier private tracker sites, a user would not dare post nefarious software and risk their account being banned not only on that particular site, but also other top sites as well since the top trackers share information with each other to keep their communities safe. But for tech savvy users who understand the risk and are knowledgeable in mitigating these threats, this shouldn't be an issue and warez sites are the best in this area.
Besides software, I would surmise that torrents trump in nearly every other category with special emphasis on media such as movies, television content, and music. I have never seen anything like the musical, TV, and film repositories that are present in top private trackers. And I mean that both in the entire file sharing world AND the paid commercial scene. It truly is a testament to the power of passionate individuals working together towards a common goal.
But the types of private sites mentioned above can be very difficult to almost impossible to gain access to even with months (or years) of continued effort. So, warez sites do generally take the edge in that respect for accessibility, although there are private niche ddl sites that can also be difficult to gain access to. Use both, if possible.
