Hands, feet and head are my priorities for winter riding. My core needs not that much more layering whether it's 35 F or minus 5F.
Here's how I Max out layer wise:
Hands- for the super cold days (19F is cold but not super cold to me). Thin tight fitting gloves (so if I need to pull my hands out to lock the bike, fix something etc.) that slip into "lobster" style mittens, which are removable from an over layer of gore tex mitten shell.
Feet- thick wool socks, good solid cycling shoes with a gore tex bootie covering them.
Head- thin balaclava with face shield and a thicker one or the hood of the rain jacket over it. Helmet.
Core- thermal under layer on top, thin sweater, mountain gear vest, showers pass jacket, for the legs fleece lined jeans and gore tex rain pants.