People scoff at stuff like 425M but in my experience, it performs very well in some of the Solingen knives I own.
Well the moly modifies the grain making it smaller and tighter. Moly also makes a hard carbide in the alloy.
This means higher edge strength and higher edge holding. The result is they can use narrower edge angles which really improves the slicing ability of the edge.
Again, I am not a metallurgist and what makes the best knives for kitchen use is dependent on just what job the knife does.
If it was just about the sharpness and corrosion resistance then the answer would be Kyocera ceramics.
They are great for doing fruit or salad prep. They do not taint anything and they are so sharp that cut surfaces even resist normal oxidation because the food enzymes are not released.
To bad their extreme brittleness and the price rule them out for most people.
Drop a Kyocera knife on the floor and you are picking up broken pieces, hit anything hard like a bone and the edge has a missing piece that you have to find before serving it.
You can buy 10 Victorinox paring knives for the cost of one Kyocera paring knife, and I really don't want or need a straight razor's edge to peel onions or potatoes.
Some companies have been playing with Titanium knives, but again the edge is not enough better to justify the price.
I mentioned the powder crucible steels before, but what I would really love to see is something in glassy metal.
Glassy metals are very much the technology of the future. (DARPA)
The price at the moment is still pretty high, more than $10 a pound, but it might come down.
More about glassy metals from Liquidmetal Technologies
http://www.liquidmetal.com/index/http://www.liquidmetal.com/news/dsp.news.04x104.asp