I never thought 2 pages of strap discussion would be interesting!
I'll second that emotion!
Since my DSLR is permanently attached to a tripod in my studio for the time being, the Canon strap is still in the box.
With my film bodies I used common black cotton web type straps which worked just great for me for more than two decades. What I liked about them besides their width (comfort) is their level of adjustability. With 3 bodies on me, I could strap one around my neck, one across my chest and the 3rd and most used one on my shoulder.
My humble opinion on your three choices:
SLR-CLASSIC: UPstrap Rubber and me don't get along. Even through a shirt, it irritates my skin. The pad doesn't seem that big so if you want to hang your camera from your body a different way from the usual, you have to move it along the strap. If it is too easy to move, it means it would probably move when you don't want it too.
RS-4 R-Strap » BlackRapid.com That is an interesting idea. Wonder how it feels in actual use. I also think I would have a tendency to hand the camera in such a way that the lens would face back.
Pro & Pro Loop Strap | Demo Page I have a serious problem with that one because I have had a set of those plastic snap connectors break on me. Plastic does not age well and there can also be manufacturing problems that make them fragile which was my case, only 6 month old. Thank God it was not a camera. But it was enough of a major problem that I will not trust one of those again.
I guess I would go with the BlackRapid. And, compared to the one that someone else gave you a link to, I like the fact that it attaches to the bottom of the camera.