ACF-50
Not cheap, and I did do a test with some metal strips and compared ACF-50 to WD40 (What else is there to do in winter) and in all honesty the WD40 did very well considering the price differential.
The bottom bracket is half ACF-50 (Least corrosion) half WD40 after about 3 months in the garden with me regularly throwing a pile of salt on top - without topping up the oil coatings. The cleaner upper bracket half I did re-apply oil too. The totally rusty part was untreated - proving these oils all help substantially.
ACF is not so easy to spray so until now I have been using both as the WD comes out a bit more misty and I can get it into nooks and crannies.
Just ordered a cheap compressor spray gun so I can spray the ACF-50 on like the Pro's do - this also uses less compared with the wastage you get using cans or bottles of ACF.
I think the bottom line is any coating of oil will do wonders to prevent corrosion... but that will probably spark the clean regularly Vs leave it all winter argument that occurs every season
With my pleasure only type of winter riding I can afford to clean the bike after every trip or two, and to leave it sat when the roads are prpoerly covered in sludge and salt.
For daily riders doing this would probably cost more in ACF-50 than the depreciation from a bit of corrosion here and there.