These Storck Bib Tight Winters come with windproof and water resistant panels and several other neat features, although they're certainly an expensive option.
So, those windproof/water resistant panels are the ones that go over your knees and your quads – the most exposed areas. They're fleece backed and stretchy so they're perfectly comfortable as you pedal. Most of the rest of the lowers are made from a fabric called Notorious which has a fleecy, ribbed inner surface that holds a lot of warm air around your legs.
The Castelli Velocissimo bib tights are good, comfortable bibtights for cold – but not the coldest – rides
The Velocissimos are made from Castelli's Thermoflex fabric which is a soft, brush-backed Roubaix-type material that's very stretchy. It's not as thick as some and there are no windproof areas but it's warm stuff.
Northwave's Blade bibs are good-quality Super Roubaix tights with enough warmth for most winter conditions and a decent Elastic Interface pad to keep you comfy.
The fabric is Super Roubaix (polyamide/elastane) throughout apart from a mesh section over your upper back. Chances are that you've used Super Roubaix before: it's brush-backed fleecy stuff and mega-stretchy both up and down and crossways so you can get a close fit without any restriction when you pedal. It moves moisture away from your body quickly too so you don't get drenched in sweat.