Well, I don't know all the details, though I'm sure someone will chime in, but this is what I know and like:
I don't like 440A and 420 anything...having used them both...
I like AUS8 quite well and 440C a little better, but it's hard for me to tell the difference. Both decent choices. Probably the best value.
VG10 is really one of my favorites....no special care of this stuff, pretty easy to sharpen, holds it very well.
I like D2 about as much as VG10. It's a lot harder to get the edge I like though, when compared to VG10. The edge retention is the best of anything I've used. Apparently, you have to take better care of D2 (being a carbon steel) than a lot of other steels, when rust and staining are concerned. I don't do food with my D2 knives, so that doesn't really bother me (in the context of staining). I really don't do anything special to my D2 blades and they're just fine, so obviously, it can't be much more prone to rusting than anything else. Then again, I'm not hacking my way through a tropical rain forest.
S30V is probably my favorite right now, but it's difficult to say since I haven't sharpened my only S30V knife. I've just never seen a knife that sharp before, and it held the edge pretty well as I hacked through a bunch of cardboard. It's still easily shaving sharp, but it lost the stunning edge it shipped with. Probably the worst value.
