If you can afford one, the 1upUSA is the rack to get. There are several versions. The best part is if you don't need to carry more than three bikes, and you usually only carry one bike, then you can get the single 1up rack, and easily add two more trays in a minute or two, and take them off just as fast.
The single 1up also fits 2 inch and 1-1/4 inch receivers. It comes with an adapter that goes on and off with one bolt. Two bikes are easy to make clear each other, multiple bike trays are staged higher, like stadium seats.
If you always carry two, or more bikes, get the 2 tray bike system, and add to it. You can also buy a cheap adapter kit that allows bikes with tires up to 4.5 inches wide (fat bikes). Also cheap adapters for very skinny road bikes tires (under 2.0 inches) .
1Up racks are not cheap, they are nearly the most expensive rack system available, but everyone who has one loves it. I do. I've had mine for 3 years, and I use it on the Touareg AND my camper that has a 1-1/4 inch receiver. I put the bike and rack on back of the camper, and when I get to my destination, I transfer the rack to the Touareg with the 2" adapter in about a minute.
If you have a couple of days to read reviews, here's a thread at MTBR.com .. Check it out on YouTube also.
1up Quick Rack Quick Review.- Mtbr.com