I have to agree with HJK - too many seek the latest exotic lowrider steel - without knowing how to sharpen it properly and, even when they do know that, without knowing why they need that steel.
My favorite knife steels are A2, 154CM, and O1, and not necessarily in that order. I find D2 unmanageable and S30V very close to that (though I do like the S30V). The 440 series is fine and, while it will serve the needs of any knife wielder in this forum, it just doesn;t rank up there with my "favorites". 12C27 is another nice stainless. 1095 seems to have gone out of style because, as HJK inferred, it just isn't "cool enough" anymore, yet it's a fine carbon steel.
Some of the Scandi-ground EnZo blades are made in O1. I own several and have scaled the blade blanks and given many away. It sharpens easily to a nice, crisp edge. Like any carbon steel, it needs a little attention or a forced patina to prevent rusting.
I think guys should pay more attention to the design of the knife and how it will suit their needs than the steel of the blade......generally speaking anyway. The only steels I try to stay away from are the Chinese steels. Are they poor? I don;t know and I don;t care, I avoid them for other reasons.