Gore tex is by far the best waterproof/breathable material. the name brand of the pant won't matter too much unless you're looking for style, and that's where the price will factor in, look for YKK zippers and sealed seams, and you should be ok.
super important thought is taking care of the material, back when i used to snowboard my ass would get soaked all the time and i couldn't figure out why cause i had gore tex, i just wasn't washing them cause they were black and didn't get dirty. to keep it waterproof and breathable you have to wash (you can use special detergent for the application) but if you rinse properly you should be ok with normal, and stick them in the dryer as opposed to air drying,
peace