No mention of Op/Tech? Their Pro strap was generally considered (around here, at least) the strap to get until the R-Strap came along. (It also comes in different colors!) I've seen Photopass folks using 'em, too. The downside is that they can get your neck a little sweaty, but probably no worse (and maybe better) than any other big neck strap.
I've got a couple of the R-Strap RS-7s. They are certainly not a perfect design, but are easily the most comfortable one. Some improvements could be made (like adding more springiness like the Op/Tech and some texturing to discourage slipping, and maybe some more QC - the two I've got now have different ways the strap is threaded through the plastic buckles), and some are unavoidable with the design (the connector is in the way when shooting in portrait mode and can be a pain when going to use a tripod.) Unfortunately, they're pretty highly-priced, too, as are the accessories. If they chopped the price in half, they'd still be more than the Op/Tech Pro strap!