Crumpler's, "Noose" is something to consider for a hand/wrist strap. Previously, I did have their Industry Disgrace neck-strap, and although very comfortable it was bulky and hard to stuff away into a camera bag. I have since returned to the OE, Canon neck-strap. I have no issues with my 70-200 F4L IS around my neck with this strap.
Everyone is different, but before you spend money on a neck-strap try to think about how you use the camera and if a neck strap is really something to invest in. Any neck-strap is going to be uncomfortable overtime with the weight of a camera hanging off. I also find it annoying to have to hold the camera in place, lest it bounce around as I am walking. Rather, if I were to invest in a strap, it would be something like a Blackrapid, but then again I am not sure how well it would work while I have my sling-bag or backpack on.