The two JNats are Suita's from different mines and both can be considered 95% finishing stones. The only reason to go to a finer stone is trying for ultimate sharpness that is usually not needed for day to day work. The one in the mail is also a Suita but courser and will be used as a setup stone.
The Norton, what can I say but wow. I went against Doctor's orders and tried it on a O-1 western iron. The chisel was set up with a med India then honed on the Hard Ark followed by stropping. I couldn't believe how quickly I had a very sharp and usable iron. The Norton Hard Ark is not cheap for a Ark stone but damn Bubba it is fast and leaves an edge that just needs a little stropping. My new recommendation for any one just starting out is just that combination. For just a little over $200 USD you would have a lifetime sharpening set up. The only kicker is the Hard Ark must be from Norton, I've other Hard Ark stones and they are no where near as fast.
More once I've two arms to work with.
From left to right, Norton Hard Ark, Nakayama Suita, Shinden Suita.