My favorite lightweight pants are prAna Brion and Columbia Pilsner Peak. They are comfortable, light, cool, and quick-drying. They are stretchy which makes them comfortable and quiet, but also less durable (I have worn some small holes in them after two years of use, but so far they have been repairable).
I also like my cheap Unitop brand pants from Amazon. They aren't stretchy, and they make significant noise while walking, but they are more durable and more mosquito-resistant. They are no longer available on Amazon. The men's version of the Columbia pants are also no longer available on Amazon, I'm not sure if they are still available elsewhere. The prAna Brion pants are more expensive, and the price varies a lot by color?!
I also like my Under Armour Pique Joggers. I haven't used them for backpacking, but they are comfortable, stretchy, quick-drying, and extremely durable. They aren't quite as light and cool as the other pants.https://smile.amazon.com/gp/product/B006QM6J4Chttps://smile.amazon.com/gp/product/B01N2JLZW7https://smile.amazon.com/gp/product/B06XRVY45Xhttps://smile.amazon.com/gp/product/B071HW9HDM