Clipless with covers or boots?

It's been a month since I returned to cycling as a means for my commute. I ride a short 15 kms round trip. The weather is changing, gonna get real cold (0 and below) and wet. The temp isn't the issue (so far). The waterproofing is. Should I be looking at clipless with foul weather covers or a pair of winter riding boots? I want the best equipment for all seasons. I'm just not sure if the clipless with covers will perform like I need them to.