Okay Tuff, you may get frustrated, but bear with me.
Hard to say what the "best" steel is, without a context. Can you see that different types of knives demand different types of steels? For a salt-water dive knife, rust resistance is probably the most important property, followed by toughness for prying, but edge holding isn't as important. For a combat fixed blade, toughess is very important, edge holding almost as important, stainless may or may not be depending on the user. A folding knife typically wants a compromise of all 3, though typically I want my folder to be a little heavier on the edge-holding side.
Think of steels as bundles of trade-offs. There are tradeoffs of things that directly affect you, like edge holding, corrosion resistance, toughness, and price. And there are properties that indirectly affect you, like machinability, ease of heat treatment, availability.
The best steel for a knife depends on the kind of knife it is, and the requirements of the user. If you live near the ocean, maybe the "best" steel for you is a little more rust resistant, even at the expense of edge holding (e.g., perhaps you want AUS-8). Here in dry CA, I might want the exact same knife, but be able to sacrifice rust resistance for better edge holding (e.g., perhaps I want ATS-34 or even D-2).
Anyway, what I'm hoping to convince you is that the way to understand steels is *not* by asking open-ended questions like "which is the best?" Those questions have no good answers, and any answers you do get will be HIGHLY misleading. There's a couple good ways to learn about steels. One way is to zero in on a particular knife, and describe *exactly* what you're going to be using it for, then ask people what they think the optimum steel is for that knife's edge geometry and for your particular uses. Even then, you'll notice the many knowledgeable people on the forums will not come to a consensus -- there are often many good solutions to the exact same problem.
I'm sorry it's not simpler than that, but there it is!
Joe
PS Yes, titanium and all the steels you mentioned are metals.
