Roof racks, hitch mounted racks, and tension mounts are the most common setups. If you want a super stable setup or are planning on carrying 3+ bikes then we think a hitch mounted rack is best. But the drawback is it requires previous installation of the hitch.
And if you want something unobtrusive, then the roof mounted racks will do. But they too require a roof rack to be installed before you can use them.
For most riders, the tension mounted racks will be the best choice. They can be installed easily, and put away easily and require no extra modifications. They also tend to be more affordable in addition to requiring no extra gear. Which is why we think they’re so popular.