Here's my recommendation, partly because I'm a career machinist, and partly because this is what I use on my bikes. Okay here goes.

I use WD40 and Starrett M1 20 Ounce Aerosol Can Multipurpose Penetrant 86430014 - MSC because they offer up a decent protective film over everything. I get very ticklish about spraying water on mechanisms, and your bike is a mechanism. Water creeps into anything and starts to create corrosion, especially between dissimilar metals. A liberal application of WD40 - allowed to dry and create a film - is the best protection you can get for a winter bike in my opinion. I also added the Starrett M1 to this post because, like WD40, it creates a film, but the M1 creates a thicker, longer-lasting film than the WD40. Very good stuff.

Here's my method for my winter bike:

1. In the Fall, I usually dig out the winter bike and completely dissassemble/reassemble, thoroughly cleaning and wiping down everything.

2. Blow (compressed air) out the frame (steel), and flush it out real good with M1. Drip dry.

3. Wax up the frame upon reassembly. I use Butchers wax, or Renaissance Wax.

4. Then I spray WD or M1 liberally on the BB, hubs, pedals, seatpost, headset, and brakes (being careful not to get it on the rims or pads).

5. Wet-lube on the chain... a lot.

So after a messy ride, I rinse off the dirt and salt and whatnot and let dry. Afterwards, reapplying the WD or M1.

I never air-blow anything on my bikes besides the chain (when its off the bike), because I am fearful of driving any moisture into the hubs or BB or headset, etc.

This method is a little anal, I know, but it works for me and I have never had any corrosion whatsoever from my winter bike.