Ideally something very corrosion-resistant that requires almost no maintenance, takes a fine edge and holds it for a while. So that rules out carbon and tool steels right away. Even a moderately corrosion-resistant steel like D2 will lose its cutting ability quickly in the kitchen because the various acids in the food degrade the edge quickly.

With PROPER heat-treatment, you'd be hard pressed to find a better steel for use in the kitchen than 12C27. IME a stainless Mora makes a pretty much perfect paring knife, bar none.

VG-10 would make a superior blade as well. I have a laminated Japanese chef knife with a core made of VG-10. It's simply an awesome cutter and keeps the edge very well.