Yakima Double-Down or Thule Roadway. They are very similar.
One advantage of the Yakima is that it comes with some sort of anti-sway feature built into the cradles. That's extra on the Thule. One knock against the Yakima is that it doesn't provide anything to lock your bikes to and it's possible to take apart the rack and steal the bikes. If your hitch has a loop or two (many do), you can lock your bikes to the vehicle. The Thule has a couple of metal loops at the base for tying down and locking the bikes to.
Some people complain that neither carrier attaches to the vehicle with a standard hitch pin and instead use a threaded bolt. Yeah, it's not quite as easy to attach them this way, but they end up more secure with less wobble.