Lol...do people actually collect strops and compare them? Can you elaborate why you consider the KnivesPlus strop the best? Is it the pre-treated leather? I have a couple of strops, a HandAmerican and a Pinewood Forge, and I see no difference apart from the compounds I use.
I'm with you, although I do have dozens of strops that I've amassed over the years. So long as the leather is firm, none is better or worse than others.
At one time HandAmerican was selling a dozen different leathers, some of them embossed with a diamond pattern, some latigo, some rougher than others, and I bought 'em all. They all worked the same except for the latigo leather, which, due to its oil content, made keeping compound on it difficult.
Spending 30-45 minutes making one out of good quality vegetable tanned (so that it will take the 'casing' treatment to firm it up) leather produces a strop every bit as effective as any sold for use with compound.
Were it to be use bare... there we get into some interesting comparisons, as certain leathers contain higher natural silicate levels, smaller cell structures making the leather more dense, etc., but when using a stop with compounds, so long as the leather is firm and flat, all work well. If you purchase one, most of your money is going into the sanding and finishing of the wooden base, and the companies just slap on an unprocessed piece of leather, melt enough compound on to last a lifetime, and put it into a pretty box.
There isn't a single knife-supply company that says that it cases its leather for the strops it sells. That means the resulting leather on the strop is not a firm as it should be, making it easier to roll an edge. You can prevent that by being careful when you strop... but you shouldn't have to.
Me? I don't need a finished wooden base, a pretty box, or four pounds of compound. I'll spend $5 on leather that I case and roll down to the density of wood, use scrap lumber, and crayon on just a wee bit of compound. Hmmm.... reading that makes me wonder why I don't just use the wood without the leather... that's what the wood carvers do!
Stitchawl