Fuori,
I would recommend finding a copy of Chris Townsend's "Backpacker's Handbook". Really the best discussion of clothing systems I've read.
My short take...
As I see it, there 3 common kinds of insulating layers:
Puffs - down, primaloft, lamilite, etc.
Fleece - fleece, pile, loose knit wool (e.g. sweaters)
Soft Shells - Woven wool (mackinaws), tight knit wool (norwegian sweaters), synthetic soft shells
IMO, insulating softshells are best for around town or for hunting - both relatively low sweat activities where I don't have to vent much.
Puffs are good for use in camp or resting on the trail. They are not good for high sweat activities nor are they good for super wet conditions, as the outers and liners tend to hold water even when made from light nylon.
Fleece (and pile and loose knit wool) are good for high sweat activities since they can be worn under a shell with zippers and pit-zips, so that opening the shell will allow the wind to pass
THROUGH the fleece to your core, providing maximum cooling and moisture transport.
In practice, I carry just enough fleece to stay warm while hiking with the fleece worn under a venting shell. I then augment this with enough puff insulation (I like Primaloft a lot) to stay warm while sitting in camp or by the trail.
I buy my clothing so that things stack up: base layer, fleece, shell, puff. Note!!! My puffs often go OVER my shell, especially when resting on the trail.
It is not uncommon for me to carry HEAVIER fleece in the wet rainy shoulder seasons like October and May, since we see cold rain then. My favorite then is thick but light polyester pile. In the colder but drier winter, I often go with a thinner and less warm 200 weight fleece. The lack of moisture makes the difference.
All this to say that I see all of the various fleece variants you've listed as somewhat the same. Only you can judge fit and thickness relative to your own thermostat. And the Wiggy's sweater is an entirely different animal. It's a puff. IMO, your winter closet should have both. I wouldn't get the Wiggys though for the lack of a hood. I consider a hood to be a must-have for any puff style jacket.
In terms of mittens, IMO there are 2 basic kinds of systems: insulated mittens and uninsulated mittens combined with liners. The Wiggy mitts you listed are the former. I prefer the latter, as it allows me to tailor the thickness of the liner to match the conditions and, more importantly, to rotate out the liners as they get wet.
I like boiled wool mitts and have learned to knit my own. The pattern is somewhat based on the old Dachstien mitts. The Dachstiens weren't available in the US during the 90s and then were imported by Ortovox (they sell avalanche transceivers) but now it would appear that the rivertine online retailer to end all retailers has them.
My copies with a different finger area...
Boiled Wool Mittens by
Pinnah, on Flickr
I generally wear these under leather chopper mitts. When it is less cold, I wear wool or fleece gloves under leather work gloves. More than you want to know here.
http://home.comcast.net/~pinnah/DirtbagPinner/gloves.txt