One difference that's worth checking out among the available base plate brands is the tow bar connection height on the toad versus the hitch height on the RV. You can usually get a pretty close idea by looking at the photos in the installation manuals that are available online and measuring from where the mounting point on your own toad will be. The closer to equal the two measurements are the better. If they differ by more than a few inches, you'll need a drop or rise adapter to bring them within the tow bar manufacturer's specs.