I have the Thule Euroway 3 bike carrier:
Haven't used it enough yet to form a solid opinion, but with the few times I have used it I've been very happy with it.
If you're going to go for a towbar mounted rack, I don't think there's much better out there and it has a number of useful features. On my previous car (Territory) I had two roof mounted Thule carriers the same as Snuffy's. My current car doesn't have proper roof rails to mount roof racks onto, so I decided to go the towbar mounted option this time.
The only 'hesitation' I have with this setup is the extra length you need to factor in when parking. And the fact that although this rack is very secure, someone 'could' take off the rear pivoting frame with little effort. If you came back to the car with that missing, you're quite possibly screwed!
Never had any issues with the roof mounted carriers. Tall enough and the bikes light enough for me to load / unload the Territory without a concern. And never drove in somewhere I shouldn't have with the bike on the roof. I did have a (self inflicted
) 'mishap' once though, where I didn't ratchet down the frame clamp sufficiently. Went around a corner and heard a loud 'BANG' as the MTB slipped out of the jaw. Fortunately no damage to the bike, as the wheel straps held the wheels to the rack. But the bike pivoted over the side of the car and smashed into the side of the vehicle leaving a nice curving / arcing dent imprint where the pedal hit the 'C' pillar between the passenger and rear side windows and rotated around as the cranks spun. Pulled over, took the bike off the side of the car, then sheepishly loaded into the rear and drove off.