A2 is also a very good material.
Based on the composition, A2 should be much easier to sharpen than D2.
Regarding the issue of sharpening SKD11, I'm quite puzzled. Many materials, such as VG10, AUS10, 440C, 154CM, etc., which have higher chromium content than SKD11, do not have the same difficulty in sharpening as D2. They also have similar hardness levels. Especially when it comes to cleaning up the burr on the edge. But looking at the composition, SKD11 does not contain elements such as vanadium, tungsten, or cobalt.