I'm not sure about their rankings, but their interface is bad, you can only do 3 rounds, and they assign a random draft order.
The Draft Network isn't bad, as long as you don't want to trade or give them $30 for a year.
I prefer PFN right now. I like to trade down sometimes, especially where we're sitting now, and no one drops to 11. Obviously, some of their rankings are off, and they don't even have Javonte Williams on their board. They also have issues with the picks. A few days ago, we didn't have a sixth round pick, and now they gave us 2 of them.