I'm a carpenter, and have tried a lot of knee pads over the years. There isn't one "best" knee pad for everyone in all situations, but these ones are pretty good.
They're comfortable. They stay in place well. They don't mar flooring. They're tough, and they would probably protect against impact as good or better than any other construction knee pad.
Where they fell short, in my experience, was their primary purpose -- after a day of kneeling, my knees were quite sore. Definitely better than nothing, but not as protective as others I've tried.
So far, the Kuny's accordion style is my favorite, when worn without the top strap. They don't stay in place quite as well as these, but my knees feel better at the end of the day. A good option, but the search for the best continues!