I've had 7 pair of brush pants over the years... I've always had two pair so that those that got soaked through wouldn't need to be worn the next day.
My first pair were of Field and Stream brand. They were useless when it came to stopping thorn penetration. I tried a pair of Filson Double Tin pants but the doubled area was in the wrong place for brush busting... I still use them for working in muddy conditions.
The toughest were Filson Tin Brush Pants. They were heavy and very tough... that didn't stop me from shredding 3 pair of them in my hard hunting days. They were discontinued and the alternative Filson pants were expensive and not in the same league.
I moved on to using two pair of Orvis Missouri Breaks brush pants. They've held up surprisingly well and I think they are reasonably priced. They are far lighter and far more comfortable than the Filson Tin pants. I'm happy with them and would buy them again.
My bird hunting buddy thought my choices were awful... as I did of his.
