BTN is ratioless, their content is perfect. What's more?
HDB is the most famous where everyone longs to be a member. Look at the number of HDBits users, they have not reached their userbase yet (20,000). Not to mention it's the best tracker in HD, it's the number one in deed. HDB staff don't need donation in the way BTN is doing now. Everyone rushes to donate when they have a chance.
PTP: you can find many alternatives where you can get the same content. I'm impressed by its number of torrents.

I don't want to compare which is the best, just make some ratings only.