My first was a Saris Bones, which I still have. I like it, but does make it a little difficult to use the trunk once it's mounted. I still use it for loaded trips in the big car to the beach and the like.
I also had a roof mount dual Thule for a while. I didn't like that it knocked about 10% off my gas mileage, bike or no bike. (Passat). So I sold it after I sold the car.
My current Honda Insight Hybrid isn't really Bones friendly, so I'm using a SeaSucker (single). It's one drawback - security. I did add one of their lock accessories that a determined thief could screw up your trunk while extricating; but I'm going to swap out the skewer for a locking one, too. Not sure why they don't have the locking skewer as an option anymore. I do like that when not in use it's small, in my trunk & leaves no visible trace.