I like Thule and Yakima. Yakima has the best latch access and Thule is really big and offers a lot of protection. They're expensive though. I've heard good things about RaceFace but never used them.
I went with the Dakine Universal Tailgate Pad. It's a nice option but after getting I decided lifting my mountain bike into the back of an AT4 was going to lead to a scratched truck or a thrown out back, so I returned it.
Instead I went with the 1Up Super Duty tailgate rack. A more expensive option but I think I'll be happier with it in the long run