Interesting thread, I like to buy clothes that last, what I wear for bushy activities is generally my everyday wear anyway.
Used to love the old M65's but I've been using US BDU's for well over 20 years and in the last few years ACU's as well. I like the options of the same pattern trousers with different colour's and material options.
The 100% cotton ripstops are great for the summer, although I have used them all year round, very comfy but the downside is they only last me a couple of years. Other options, depending on which style, are a 60/40 cotton/poly ripstop, nice to have a bit more cotton and very durable. A 65/35 poly/cotton twill also very durable and a 50/50 nylon/cotton ripstop, again, very durable, there is also an advantage on drying times with less cotton content.
To give you an idea of what I mean as durable my first pair of ACU's by Propper are 50/50 mix, worn on average 4-5 days a week and are now at least 7 years old, still going strong, due to my lifestyle I'm VERY hard on my clothing!
I've loved my Fjallravens Barents but they're way more expensive
and no where near as tough.