First a list of what I have:
10k naniwa ss, natural slates app 8-10k, 10-12k (it has been suggested by an experienced honerthat these grit estimates are a bit ggenerous, but that's by the by).
I am trying to work out which next coarsest stone I should get out of the naniwa 3k and naniwa 5k, also bearing in mind that I MAY eventually buy a 1k to complete the set.

So the question is 3k or 5k? Thanks in advance, ed.