My experience with cold weather clothing:
Feet: Thick merino wool socks are the warmest socks available.The reason that wool outperforms any modern man-made material is because of the way that wool deals with moisture. Moisture is wicked deep into the yarn itself, which means that wool can absorb a great deal of moisture before it becomes saturated (and cold.) This is ideal for your feet, because feet put off a great deal of perspiration (even in cold weather) and your feet are wrapped in non-breathable layers (neoprene socks) so the moisture doesn't have a way to escape. Wool socks soak up that moisture and keep your feet warm anyway.
Smartwool's xtra heavy merino wool hunting or mountaineering socks are the warmest and most comfortable I have used (and I've used lots.)
https://www.smartwool.com/default.cfm
You can often buy them at 1/2 price at
www.sierratradingpost.com
Keep your boots laced a bit loose. This will keep the blood circulating to your feet.
Legs: Start with a base layer of some sort of polyester wicking long underwear. Polyester is better than polypropylene because it doesn't retain odors and is more durable.
(Why not wear wool? If wool is so great for socks, then why not wear it for undewear? The answer is that wool takes a long time to dry out. While wool has better performance than any modern polyester material, if you dunk yourself in the river, it will take a LOT longer to dry out than synthetic material. If you are absolutely certain that you aren't going to get wet, then go with wool. Otherwise, polyester is a better and safer choice.)
My experience with polyester wicking base layers is that they all work about the same. I've used lots of different brands (Patagonia Capilene, North Face, Marmot, Campmor, Thermax, etc.) and can honestly say that there is no real difference between brands. Something with a brushed, fuzzy inner surface will tend to be warmer than the lighter weight smooth fabrics. Buy what's on sale, and don't pay extra for name brands. Fit them relatively snug, to keep your "tackle" tucked in close so you don't freeze off any important parts of your anatomy.
Over the long underwear, layer on a pair of heavy pile pants. The warmest I've found are made by Cabelas (and they also have the benefit of being some of the cheapest as well.)They are made from heavy weight polyester fleece.You can find them here:
http://reviews-cdn.cabelas.com/8815/942517/reviews.htm
That said, lots of companies make fleece wading pants, and coupled with a heavier "expedition weight" pair of long johns, a lighter weight fleece pant will keep you warm enough in any temperatures where the water is still liquid. Again, a snug fit will be warmer than a baggy fit.
Torso:
Start with a thin wicking base layer, made from polyester.
Then, layer directly on top of this base layer, a very lightweight, trim fitting wind breaker. Why? Shouldn't the windbreaker be on the outside, you ask? Well, it's purpose here is not to protect you from the wind, its purpose (in conjunction with the thin base layer) is to create a thin, warm, semi-moist "microclimate" right next to your skin. It slows down (but doesn't completely stop) evaporative cooling which is the result of your perspiration getting wicked off of your body by your high-tech base layer.
Wicking and evaporation are good, but your body will continue to put off vapor (which is cooling) so long as the climate around it is dry. A lightweight, breathable windbreaker will provide just enough of a barrier to slow this insensible perspiration, and slow the evaporative process enough to reduce cooling.
There are companies that make single piece garments that take the place of this two piece (base layer under windbreaker) approach. Marmot's "Driclime" windshirt is an example of this combination garment:
http://marmot.com/products/product.php?cat=cloth&subcat=13&style_id=I5607
Mountain Hardwear's "Transition" shirt is another variation on this theme:
http://www.mountainhardwear.com/Product.aspx?top=1&cat=25&prod=832
Next, layer on some insulation. This can be fleece, or some sort of synthetic fill garment. (Notice that I left out down filled garments. Down is wonderfully warm, but as soon as it gets wet, it becomes useless, and takes forever to dry. Not good in a sport where you might get dunked in cold water if you slip.) My choice here is a lightweight insulated jacket. They are less bulky than fleece and lighter than fleece and warmer than fleece, and the nylon shell on an insulated jacket renders them very wind resistant. Fleece is, however, more rugged, and there are windproof fleece fabrics available (which are even more heavy and bulky, however.)
My favorite lighweight insulating layer is currently the "Thermawrap" jacket from Montbell:
https://www2.montbell.com/america/asp/products/Spg_shosai.asp
Similar designs are available from other sources that cater to climbers and ultralight backpackers (Golite, Wild Things, Marmot, etc.)
Top off the torso with a lightweight Goretex (or other similar fabric) shell jacket, and you're done. My personal preference is a super lightweight shell that I wear under my fishing vest. Because I'm wearing it under my vest, I don't need all of the pockets, nipper-holders, and other fancy (and expensive and bulky and heavy) gew-gaws that adorn most "wading jackets" made today.
William Joseph's "ultralight rain jacket" is the perfect jacket for this lightweight approach.
http://www.williamjoseph.net/clothing.php
Hands:
My favorite fishing gloves are both made by a company called Cloudveil:For when conditions allow some exposed skin, Cloudveil's "two trigger" glove works better than traditional fingerless gloves because it keeps your pinky and ring finger covered, while exposing the tips of your thumb, index finger and middle finger. I don't ever use my pinky or ring finger when stripping and handling line, so why not keep them covered and warm? They have grippy palms, windproof fabric, and quick-drying materials all around. Not much to improve upon here:
http://www.cloudveilfishing.com/product/S6A9000/?search_field=trigger
For times when it's too cold to have any fingers exposed, the Cloudveil Ice Floe glove is a nice compromise between warmth and dexterity. Not nearly as much feel as a fingerless glove, but a lot more than the typical ski glove. If it's so cold that your hands need more protection than these gloves can offer, you really should just stop fishing and go find a warm place where you can drink some hot chocolate:
http://www.cloudveil.com/mens/v-handwear/CV08030/
Head:Wear a warm, windproof hat. The warmest you can get is a full-on balaclava style hat that protects your neck. Alternatively, you can wear a regular hat, and couple it with a fleece "neck gaiter" to keep your neck warm.I'm partial to this style by Outdoor Research, because it is windproof and very warm. Lots of other options are available, however.
http://www.outdoorresearch.com/home/style/home/headware/cold_hats/balaclavas/83825
dave..