For serious winter cycling (no idea on temperature, just know the water bottles would freeze solid with hours still to ride) I found my SPD sandals to be the best thing to wear.
Mainly because they have lots of adjustment, so liner socks, thick merino socks, long sealskinz socks would all fit nicely without cutting off my circulation and getting cold feet through that. Then waterproof covers over the whole lot. With goretex overtrousers stopping water going down the top of my socks, I never suffered wet feet. Goretex boots always seemed to fill with water eventually.