What type of content is on there?
Torrentleech is like IPT, but without porn and freeleech, which is pretty much why IPT is so easy to build ratio with and TL isn't. It is basically the exact same content otherwise, but without a seedbox or 24/7 seeding, you're going to have a bitch of a time keeping your ratio up. Luckily I have the luxury of 24/7 seeding. It's basically a nice backup to have in case IPT ever goes down.
What's so good about IPT? Can someone spare an invite?
That question makes it sound like you haven't ever used a private torrent tracker, but if I'm wrong I apologize and I'm not trying to be a dick. It's just that IPT is, for lack of a better term, the Pirate's Bay of private trackers. You'll get the most content, the best upload speeds, and the easiest ratio to maintain (as outlined above) of pretty much any tracker, anywhere. Except it is private, so the chances of you getting nailed by your ISP or anyone else are a lot lower. I mean, there are always risks, but with Pirate's Bay anyone that can download uTorrent can get your IP address and see that you are downloading/seeding the illegally obtained copy of Big Booty Bitches XV. With a private tracker at least they had to get an invite from somewhere and maintain a ratio/avoid HnR's to see your IP address. A site like Torrentleech is even harder to get into and keep ratio, so it is even less likely you'd get in any sort of trouble there. But IPT is light years better than any of the public trackers still.
If you already know what a private tracker is and I'm over-explaining, sorry about that, I just wanted to be complete. The answer then would be that it has fucking everything, and a ton of members, and a ton of speed, and ratio is just a freeleech porn download away. Unless it is a really old and obscure torrent, I almost always max out my speed with IPT.
That being said, I still tend to use more specific trackers for stuff like TV shows (I use BTN because of the RSS feed it has, so all my shows download automatically in 720p, mkv format, without me having to look for them) so that I spread it around and because some are easier to use for certain things, but if, for example, BTN goes down because the season finale of Game of Thrones is due up, I know I can always get it at IPT just as fast. If you could only have one torrent site, IPT would be the one you'd want.