I tried a pair of custom built Russell boots, they are really nice especially if you have screwed up feet like mine, they are built for your feet and yours only. A little bit of a hassle to get measured up and ordered but worth the trouble.

Insulation up to 400 g's can be added to nearly any style they build. Butthey are all leatherso you have to keep that in mind when the need for 100% waterproof is a must. You have to keep lots of oil on them.

Check out their web site.