There's "carbon steel" and there's "carbon steel." By definition steel is an alloy of iron and carbon. So, in one sense, all steel is "carbon steel." Some steels are "high carbon." "High carbon" is a term of art which means that the alloy in question has at least 0.50% carbon by weight -- except in the EU where anything above 0.45% is "high carbon."
Any steel alloy which contains at least 13% chromium is referred to as stainless. Knives with between 5% and 12% chromium are referred to as semi-stainless or stain-resistant. Materials and knife guys call any alloy made up of 4% or less chromium "carbon."
So far, the other guys responding to your questions have all been talking about carbon (i.e., not stainless) knives, because they think that's what you're asking about.
Unless you're an extremely good sharpener, almost all of the high quality high carbons and tool steels, and a few of the better stainless alloys work about equally well. Edge quality tends to be far more dependent on edge geometry, maintenance routines, use, and sharpening skills than on the identity of any particular alloy.
ZDP-189 is a metallurgical powder (aka PM), with 3% carbon and 20% chromium. Because of its chromium content, it's not only extremely stainless but is not referred to as a "carbon" alloy. It's not referred to as "stainless" either, because PM conveys so much more information.
As a class, the metallurgical powders (aka PMs) are something of an exception to the practical rules of "most good steels tend to be very much alike." Compared to other knife alloys, the powders tend to be extremely strong (another materials term) and are almost always hardened to a very high degree. That means that sharpening is usually somewhat awkward, but that edge holding is usually extremely good (they can also be very chippy).
People new to high-performance knife universe are often very attracted to PMs because they associated with very hardness. But what the noob doesn't know is that hardness numbers can be more distraction than vital knowledge. As a property, very high hardness is almost always double edged in practice for the reasons already mentioned: good wear resistance; difficult and unpleasant to sharpen; stay in true, difficult to true when they do ding; chippy; etc.
Several of the best metallurgical powders are extremely expensive, including ZDP-189 and Cowry X; however the current high-performance PM darling, Bohler 390, is more reasonable. CPM-154 is another high-performance, high-vale powder. SG-2 is well priced, but you want to be careful as SG-2 knives are often prone to chipping.
If you're looking for a knife made from ZDP-189, you're looking to spend a lot of money to replace occasional sharpening with very occasional sharpening. To my mind, not a good tradeoff -- but opinions differ.
By and large, guys who make a big deal about alloys are knife collectors and not cooks. Nothing wrong with that, but if you're all about the cutting consider -- as long as the knife is made from any one of many good alloys -- other things should be higher priorities.
Unless you're throwing a LOT of money at the "what knife?" problem, there are going to be some trade-offs. And even then, not only is there no single best knife for everyone, there's probably no single best knife for you. The thing to do is to figure out what things you want most, and using those bases limit the range of possibilities to a group in which the only choices are good ones. After that, throw darts.
If you prefer "single steel" to san-mai, your choices become limited. Without cladding, many of the prestige alloys fail too often during the heat treatment, raising keep costs too high for their use as single-steel knives.
There are many excellent knives made with Aogami Super. But, like Jon, I don't like them. In my case it has more to do with other things than with AS itself.
The big Sabatier makers importing into the US -- K-Sab, Mexeur et Cie, and Thiers-Issard -- use the same carbon steel now that they did in the "seventies and eighties." If you want a knife of the sort that kokopuffs loves (I love them as well), they're easy to buy. Older Sabatier production is also readily available NOS, and has its own, slightly different charms (love those too).
One of the two chef's knives I use the most is a 51200 (high performance carbon) wa-gyuto (Japanese handled chef knife) with a Sabatier profile. The other one is a "laser" (extremely light and thin" wa-gyuto made from some type of semi-stainless. They are very different from one another; but the distinctions in their characters are not based in their respective alloys.
Edited by boar_d_laze - 6/27/13 at 7:26am