Personally I find that either I'm doing low intensity physical activity and I can just put on my Sorel Glacier XT boots and Hestra Army Leather mitts and stay warm, or I'm doing something more high intensity and my feet and hands only need normal boots and gloves.

In both cases I wear a thick merino base layer, fleece midlayer with varying thickness according to temperature and activity level, and GoreTex Pro outer layer that has zippers under arms and along thighs such that you can adapt ventilation seamlessly to variations in activity level. This works nicely from +5 C all the way down to -30 or -40 C (depending on wind chill and humidity, you might not last very long at -40 C though).

I use it for a motorcycle jacket.