There was some positive talk about Red Kap earlier in this thread and I want to confirm that these are sick.
I was thrifting and found a pair of double knee pants they make (have no idea what they're actually called) but they are nearly perfect. They have a very slight taper that's still loose and baggy in the thigh and knee, but the leg openings are small enough to cuff easily and don't eat your shoes.
The canvas they're made of reminds me of like a standard Carhartt duck canvas pant but more flexible and soft, they're comfy but the material seems durable. Only complaint I can make is the logo near the left knee, but it's small and could be removed with some careful work. Gonna have to look into buying more!
Also found an older but only slightly worn pair of black Levi's 550's, I swear these are the holy grail if loose pants for me. If you find a size or two above your actual waist size, you've found the perfect loose fit.