First a little theory...
Winter clothing should maintain you core body temperature by:
Transporting moisture away from your skin and vent it to the outside, leaving your insulation dry
Keep a layer of warm air close to your body, preventing cold air from convecting heat away. Protection from wind is part of this.
Keep precipitation from wetting your insulation and your skin.
I'm an ultralight hiker, so I don't buy heavy-duty shells like Cordura. Resistance to abrasion is the biggest challenge, IMHO. I live in the Pacific Northwest where constant drizzle is a problem for lowland hiking. At elevation, it gets cold and snowfall can be heavy. Trails exposed to snow melt run-off. can be literal streambeds where footgear/dy feet are the challenge.
What do I do? Depends on the weather conditions and the level of exertion.
Hiking with a light load in 45F rainy weather is typical. Your perspiration is working on the inside and rain and wet brush are soaking the outside. I wear a light layer of polyester under light breathable rain gear: Patagonia Capilene polyester bottoms and tops with Marmot Precip raingear over the top. The base layer can be chosen for the temperatures. For colder weather I like Power Stretch stuff. If you want more durability in the outer shell, you can go with some of the tougher Gore Tex materials. Some people like merino wool base layers. I don't care for wool, but the idea is the same: get the moisture away and keep the warm air next to your skin.
If it isn't raining, then the ultralight solution is to wear a windshirt over the base layers-- a simple windbreaker that weighs 3 or 4 ounces and is windproof, but more breathable than raingear. Most hiking wind gear is water repellent and will survive a short light rainfall, but will soak through over a long rain and the seams aren't sealed.
One myth: the idea of truly breathable rain gear. If you are working hard it is too easy to overcome the ability of breathable fabrics to move enough moisture to the outside. Tests have shown that ventilation is what works: venting pockets, vented back cowls, armpit zippers and the like are what can keep you from getting your insulation wet.
Insulation:
Because of the wet climate, I prefer polyester insulation like Primaloft. I don't use down and IMHO, it is best suited to cold dry climates. Same issue for sleeping bags. If you keep it dry, it will keep you warm. Get it wet and you are hosed. Synthetic fills will continue to insulate if damp where down will turn to soggy lumps. You can wring out a synthetic fill garment and put it back on and your body heat will help dry it-- if you are out of the rain.
You get into two scenarios with insulation: what to wear when working hard-- hiking uphill, etc and what to wear when you stop. You will find belaying clothing in mountaineering clothing catalogs-- heavily insulated jackets and pants to wear when stopped or belaying a partner on a climb. It's the same issue on a winter hike-- you work hard climbing up hill and then you stop for a break or camp. That's when you need the heavier insulation.
Polyester fleece: good stuff, but it takes up room and isn't as light. For moderate and wet conditions it is great. I don't think much of windproof fleeace-- it is heavy and doesn't have the loft. I've seen some that was really hard to dry once wet. A fleece under a windshirt or rain shell will keep you warm well below freezing. If there is no wind, it is great as an outer layer and ventilates well. Fleece is by far the best buy for warm outdoor clothing.
Gloves and hats:
I like shelled fleece gloves and a fleece beanie under a hood for cold-weather head gear. If I'm working, then leather gloves are best for me. When I'm hiking, I use a pair of Mountain Hardwear gloves that are made like a rain jacket-- breathable outer layer, a very thin micro-fleece lining and synthetic leather reinforcements on the palms. They keep the cold wind and rain off without being too clumsy and are super light. Once it gets really cold I use insulated mittens; ones made for skiing work fine for me. Outdoor Research makes a bunch of goods hats. Their "sombrero" style rain hats are good and they make a Peruvian style beanie that stops the wind and insulates. It is good for sleeping in too and it fits in a coat pocket. Perfect under a hood. My favorite all-round hat is a Tilley T4 canvas rig with a wide brim and a chin strap. My hat band is braided 550 paracord-- about 25 feet!
Footgear:
I use Gore Tex boots in the winter. Tests have shown that they dry more slowly once wet, but I think that is more of an issue in spring/summer hiking when crossing streams and such. There are more brands and models all the time. Other than than, a pair of well treated leather boots and layered socks are good. Carry spare socks. Insulated rubber "pack boots" are too heavy and clumsy for my taste-- better for sitting still in a boat or blind than walking any distance in. I don't have good sub-zero experience and I'm all ears on tips on boot and sock combinations from folk who winter in really cold places.
Other items: a fleece scarf and a pair of good sunglasses will help.
Expense:
Unfortunately, the high performance gear can have the highest price. BUT, if you know the principles, you can use less expensive gear and still be very comfortable.
Base layers:
Brands like Patagonia and GoLite have great base layer materials. You can also find very serviceable stuff made by Duofold and sports labels like Nike. Most stuff made for running works great as hiking clothing. You can find loads of good polyester base layers in Target, Ross, and Marshalls--- you don't have to shop at REI and Cabella.
Polypropylene is still around, but it ut seems to be over-run by polyester. One study found that much of the wicking properties of polypropylene came from the residual oils used to manufacture the stuff. Moderm polyester yarns are fluffed up in all kindsof ways to make them wick and feel better. One great buy on polypropylene layers are the Army surplus tops and bottoms, although they are "expedition weight" and I would want it to be good and cold before needing them.
Rain Gear: Frog Toggs and DriDucks make cheap raingear that is super light and cheap, but it doesn't hold up in brush and sitting on rocks, etc. Work-style rain gear is tough and ok for short term stuff if you look for ones that have good ventilation. I would look for good used stuff first.
My way of getting good buys on outdoor clothing is to check thrift stores often. I got a $125 Patagonia Houdini windshirt in a thrift store last week for $20
eBay and garage sales are other sources for me. There is a local hiking store that buys and sells used gear and I'm able to trade my thrift store finds for gear that I want.
