I've been really happy with ATS34 and ATS55.
Both are reasonably tough and hold an edge for a fairly long time but still aren't hard to sharpen. Stain resistance is pretty good. I took a knife with an ATS55 blade (uncoated) into the ocean not to long ago and the only care I took to prevent rust was to oil the pivot area with rem-oil and wipe the blade down with dexus gun oil wipes. Most of the time it didn't rust at all, one or two times it had small spots that could be buffed off easily.
I haven't ever used any of the new steels that are supposed to be so great like the CPM series and BG42. But from what I've heard and read, BG-42 is just modified ATS34, and doesn't perform that much differently, so at least in my opinion the added cost probably isn't worth it. I don't know what to think about the CPM steels, after looking at the cost of barstock I know I won't be trying any of it for awhile, but then I'm not getting any profit from the knives I make.
MAybe since these are custom knives, you could give people a choice of the steel they want when they make the order, and just limit the choices to a certain set of steels that your willing to work with.
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It'll feel better when it stops hurting.