Cheap, usable "tactical" backpacks (40L)? Any experience?

Do you have any comparative experience ? Mil-Tec US Assault Pack or Brandit US Cooper or other "tactical" backpacks (approx. 40l)? Robustness, water repellency, practicality, comfort, etc.? Suitable for outdoor use in urban/forest areas with rough, fast, and demanding phases over several weeks? Specifically, it is about temporary equipment for changing training groups, who will…