The Cold Steel Voyagers are very good knives. When asking if they're the best, the best for what?
The lockback mechanisms on the Voyagers, in my experience, are very strong. In pure lock strength, they are almost certainly exceeded by the REKAT Rolling Lock folders, the Chris Reeve as well as other makers' frame lock folders, and the Benchmade Axis Lock.
Are the CS Voyagers' locks strong enough for what most folding knives are designed for? More than strong enough. What's more important than pure brute lock strength is lock reliability. Any folder's lock can fail under the right circumstances, such as if it's not kept clean, if overstressed in a way not intended, etc.
The Voyagers have excellent edge geometry, and are fairly easy to resharpen. I personally rate them as excellent middle-end working folders. (by the way, the manufacturer CS contracts to make the Voyagers in Japan also makes knives for Spyderco, Al Mar, Outdoor Edge, SOG, etc.)
I have not tested the knives like in the video, because I want to use them. CS admitted the extreme tests shown can ruin a knife. Plus an older, much-used knife wouldn't test at the same level as a brand-new knife.
Jim