For serious outdoor use, I go for pants made of nylon or other synthetic material. In any climate where snow, rain, or wet conditions are at all likely, you want to stay away from cotton. For cooler conditions I like the Mountain Hardwear "Winter Wander Pants", or the Marmot "Scree Pants". For warmer weather there are many brands of lightweight nylon pants with zip off legs.

Carhartt pants are tough and I find they are great for work around the house etc. However since they are cotton I stay away from them for serious outdoor or potential survival situations. Likewise the Duluth Firehose pants are cotton, if I'm not mistaken.

Cotton may be OK for those of you who live in dryer climates, but can be deadly if you get wet in a survival situation.