The mountain pant. They are extremely durable, comfortable, and adaptable for use during all seasons (just add a warm base layer and some gaiters for late season).
WT Equinox. Then I bought Timberlines... which I wear as often as possible. Slightly thicker, very warm with good base layers. Can't go wrong with either depending on your pattern preference and at least the Timberlines come in solids.
For an all around pant I would have to go Mountain Pant. I have ran mountain pants for years and after a lot of tough miles they are still going strong.