If I was only buying one stone it would be this one. The 325/600 (course/fine) 8” DMT with the base. It’ll run you about $90-100 on Amazon if you catch it at the bottom of its price swing.
I use steels that necessitate diamond to cut their carbides but even on normal steels you’ll cut faster and have less issues sharpening blades on diamond. If you take care of that stone it’ll last many, many years.