Keep in mind none of the fabrics you've mentioned are waterproof or worth seam sealing. Some options:
1. M50/M90/30d/70d ripstop- will be fine in snow and light rain, but not waterproof and will wet out in sustained rain.
2. Use the above for the back and 30d silnylon for the front. Works great in rain for a while but after a while you'll get wet. Silnylon is surprisingly durable because it's so slippery and doesn't snag.
3. All Sil. Not breathable, but waterproof, and breathability on the legs usually matters less than torso.
4. Find some WPB fabric. Probably a bit heavier and more expensive.
#2 is a good compromise for me for 3 season use if I'm expecting rain, although I don't usually use them in winter.
If you plan on sitting in them a lot, just reinforce the seat with some 70d sil or something lightweight/PU coated.