Best Rack - 1up USA Quik Rack. Made of aluminum, folds in half. Really, really, really expensive though:
https://www.1up-usa.com/product/quik-rack-single/

Cheapest - Swagman XC Cross-Country 2-Bike Hitch Mount Rack. It almost doesn't touch the frame, but it does a little. It's a "hold by the wheel" style rack.
https://www.amazon.com/Swagman-Cross...dp/B0001VO1YY/