hestras are nice, but you can get the same performance for less. i have marmot mitts that keep my hands warm on the coldest of days. they have goretex in them and it seems when i talk to people that say they always have warm hands, they also have goretex mitts.. so you might consider looking into that before you drop some dough on some bdog mitts that will be more fashion than functionality
Woah, B-dogs are most definitely not warm enough for 0 degree weather, even without windchill.. They are a dope mitt, just not warm enough for what you are looking for. Oakley just came out with a few new mitts.
black diamond, arc'teryx, and hestra all make super quality gloves that will last a lifetime. they are really expensive and you can certainly find gloves which will be about as warm for less money, but its really hard to match the quality and durability of these companies. look for "guide" models especially, as they are designed to be the toughest and warmest of them all.