Neoprene booties here, although I do keep eyeing dedicated winter shoes since the booties don't hold up off-road with the mountain or CX bike.

One thing I did which made a surprising amount of difference to me was to tape off the vents on the bottome of the shoe. The ones by the toe I did from the outside. I then pulled the insoles out and taped over all of the openings there, including the cleat area. Kept the wind out as well as helped with water splashes on wet days. I just used gaffers tape (like duct tape).