I thought the Seagull had that title (World's World TLR).

Seriously, however, one of the nice things about the Rolleiflex is its ease of operation. Now, I'm speaking of a camera that is in good condition. Focusing is effortless, and the camera is very simple to use. Flip up the finder, focus, shoot. You can see the shutter speed and aperture from above -- no need to check the front of the camera.

Crank the film 1/2 turn and move the lever back and you're good to go for another shot.

I'm not saying that a Mamiya also isn't a good camera, because I've always heard good things about them. But, a Rolleiflex is hard to beat, if you don't require interchangeable lenses. Downside: Many of them will need to be serviced, and if it hasn't been serviced, you should assume that it requires it.