Here is quick summary of the advantages and differences between several camera straps that I own - things that proved important to me.
1) Comfort
2) Security
3) Flexibility
4) Quick access
5) Easily and quickly removed
Black Rapid RS7Does most things well.
Well made. Comfortable.
Handy anchorage for optional storage pockets (if you really want them there.)
Anchorage to the camera can scratch the camera.
Direct anchorage to the tripod socket is not as strong as if a plate is used to counter tortional force.
Strap anchorage must be removed to mount camera on a tripod.
The quick disconnect can be opened with one hand, a liability if careless and it makes it easier for thieves when traveling in foreign locales.
The camera connection has a potential weak link at the end of the locking swivel hook that can wear and fail. (But I have never heard of one failing to date...)
Cotton Carrier Awkward twist required to free it from the clunky metal chest plate; especially so with a long telephoto.
Strap anchorage must be removed to mount camera on a tripod.
I just did not like it. Personal preference, so personal bias involved.
Carry Speed CS-Pro Better anchoring system to tripod mount by using a standard Acra Swiss plate with a swivel ball for attaching the camera strap mount. Stronger and more flexible as it can go off and on a tripod without removing the strap anchor from the camera.
The camera strap has a double lock disconnect which is more secure and works well.
Supplied with a second security strap for long telephoto lenses.
Comes with an easy-to-use wrist strap which connects to the same mounting ball. A secure feature to have when mounting and un-mounting the camera from a tripod.
Widest and most comfortable strap of the lot. Great for heavy lenses.
The ball and socket connection is probably overkill, so that appeals to me. Very very secure.
Luma Labs CinchA solid design by a small firm without a big advertising budget.
Uses both the tripod mount and one camera body strap lug; providing double security anchorage and less stress on one mount.
Strap anchorage must be removed to mount camera on a tripod.
Offers a well designed adjustable strap for keeping the camera at your side, and adjusting the strap on the fly. Takes some getting used to, but it works and is a good concept.
See:
http://luma-labs.com/products/cinch for more information.
So which is best? There is no winner. They all offer advantages and it quickly becomes a personal choice based on your priorities. If you carry a camera around all day, comfort is a primary concern. Cotton Carrier and Carry Speed are best in that regard.
If you are carrying a heavy telephoto on a less expensive DSLR, the tripod mount may be over stressed. The Luma Labs Cinch and Carry Speed (when using the second lens strap) are the best choices. Both have a more secure mounting system.
If you want to carry some very small items on the strap, the Black Rapid system offers pouches that are easily attached to the strap. This convenience is important to some folks.
If you want to carry two cameras both the Cotton Carry and the Carry Speed have good options to address this. This allows flexibility without having to buy two straps from the onset and easy conversion back to one camera.
At the end of the day, only you can decide what works best, and you often can only do that if you try out the most promising straps for several days.