Just went through a switch from hitch to roof.
I really liked the easy access of my hitch rack, and although the Hollywood Team Rider left something to be desired in terms of quality and ease of loading, it was nevertheless solid. But to go hitch again, I'd go Sportworks.
One problem with the hitch was access to the rear liftgate of my Subaru. Another was the potential of getting rear ended. With two or three bikes on, brake lights and turn signals get obscured and that worries me in heavy traffic, plus a lot of cars are eager to pass close to tires and rack parts are extended out past the sides of the vehicle. Also, it stands to reason that if I got rear-ended, rack loaded or folded, the force of the impact would go through the rack straight to my car's chasis, bypassing my bumper.
I decided I would rather accept the responsibility of not driving under anything low enough to hit, i.e. fast food drive-thrus, car ports, etc., than accept the randomness of any person rear-ending me.
So after looking at the Thule V2, the Sportworks Bob Ratchet, and the potential of converting a Saris Cycle-On to roof mount duty, 2 months ago I purchased a pair of Yakima King Cobras.
The red knob is the weak point of the design. Screwing it, unscrewing it, making sure it stays tight all smacks of some kind of garage engineering that I figured was beyond Yakima's quality. Regardless, I still prefer dialing the little red knob over removing front wheels and fretting about QR tightness and disc rotor alignment. And as pointed out, the rack is completely "hands off" of the frame & seatpost: rims and tires are the only things touched.
I've done two pretty long trips with these racks, one 5 hours and the other 3 hours of continuous driving at speeds of up to 90 MPH, and although that half-witted red knob tends to loosen with each click of the odometer, the rear-facing bikes stay in place with a minimum of bug splatter, side-to-side wobble, and noise -- all problems I worried about prior to purchasing.
The red knob loosening is really as simple as attaching a safety wire to keep it from vibrating loose. Other solutions include a dab of thread lock or the substitution of a nylock nut inside the knobbie (which would make turning the knob even less fun when loading and unloading). I sincerely wish Yakima would address this one outstanding issue (I've emailed them; they won't even acknowledge there is a problem regardless of tons of threads like this one and a handful of online reviews that cite the issue).
I'm also finding I like having the bikes on top of the car if I park it for a post-ride bite to eat -- better visibility, from more vantage points, makes them easier to keep an eye on, and I don't have to worry about some grandma in a Coupe de Ville smacking into my pride and joy while trying to back out of her compact parking space.
In any case, I like the rack, I'm 90% happy with my choice, I still use a hitch add-on when I have to carry a third bike but feel liberated that I have unobstructed access to my lift gate and that the dogs don't have to trip over the rack every time they get in and out of the car. Even with the "non-existant" red knob problem, I'd recommend the Cobra so long as you realize the knob can become an issue and you tighten it and check it accordingly.