Huge variety of choice, so many brands, so many designs.. it can be overwhelming. Just like with shirts, the good thing when it comes to climbing apparel is that the only thing that matters is comfort and design if you will. You need to be able to move freely and not get annoyed by a restricting, loose or tight pants. The design then is totally up to you! Some models will have reinforced knee pads and often a diamond shaped gusset for maximal freedom of movement.