Tanaka AS and Nakagawa Blue 1 are both pain in the butt to Polish, TF white 1 is also pretty ***** to polish.
As for stainless, i find Takamura Hana and Pro/Uchigumo is one of the hardest to sharpen.
As for stainless, i find Takamura Hana and Pro/Uchigumo is one of the hardest to sharpen.