mine are new to laying, haven't gone through a winter yet, but I also have Australorps, I also hear BSL (which I have) are good layers...will have to get back to you on this subject
Leghorns. Mine were champs all winter long - they are 1/day layers, each one of them. They never miss a day! You do have to be careful for frostbite, though. No lights for them last year. (my other breeds all had lights on a timer so can't say for sure how they would have done without that).