Hardway;
Of the 400 series of steel, 440C is the top of that line. It is used very much in kitchen knives due to it's content of chrome,17%, and very rust resistant. If a knife maker uses 440C, it will be listed as 440C on the blade. Other makers using 440A & 440B stamp 400 series, or 440 on the blades trying to fool the buyer into thinking he is getting 440C. Because of this, 440C has gotten a bad rep because of the 440A&B being passed off as 440C.
If heat treated properly, 440C will be around 57-58RC and that is hard enought to hold a good edge. Several knife experts, including one who is a Material Engineer will tell you that S30v is the best stainless steel on the market today for knife blades. surpasses other SS in edge holding, toughness, and abrasion resistance and has 14% chrome for rust resistance. It is also one of the most expensive steels to buy. That is the reason you will never see it in cheap knives.
Another good steel is D-2. Has been around for many years and can be heat treated to 60RC. It has only 11-12% chrome and can not be called a stainless steel which starts at 13% chrome.
Another one to stay away from is AUS6, a Japanese steel that is in the ballpark with 440B. AUS8 is better, similar to 440C and is used by Coldsteel in some of their knives.
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