For refining S30V & D2, I like anything diamond.
On S30V, anything in the 325 - 1200 range, chosen to your edge preference in diamond, will leave some degree of toothy bite. With my own S30V knives, I tend to hone them with the 600 most of the time, and this steel becomes one of the simplest of all to maintain with that alone.
On D2, it can polish very well beyond that, using diamond compounds at 3 micron and finer on hardwood - the 3 micron is where a mirror polish starts to come up fast. Again, choose the finish according to your preference. Many will say that D2 doesn't take or 'like' a polished edge - but it certainly does respond well, if that polish is done with diamond on a hard substrate. That's where I've left most of mine in D2, with a polished finish done with 3µ diamond on hard, tight-grained wood. I emphasize diamond on hardwood, because a softer substrate tends to introduce more edge-rounding issues in D2, due to the steel's very large chromium carbides. You want something capable of cleanly shaping those carbides while using the lightest touch possible - which is why diamond/hardwood works so well with it for polishing.
The 440C/9Cr steels will respond to most anything manmade. SiC eats it for breakfast, making heavy grinding a breeze (this is true for D2 as well). And for refinement beyond the grit rating of most SiC stones, good quality aluminum oxide stones and polishing compounds will handle it well. 440C is my threshold at which natural stones (like Arkansas) struggle and stop working well - so I limit work with it to the synthetic stones.
With most any steel I've ever tried, a good quality diamond hone in the ~600 range will leave some great toothy bite. If I were limited to using or carrying only one hone for all needs, I'd carry a 600 diamond. When I mention 'good quality', I mainly refer to DMT's hones, which I like because they're better than any I've tried in minimizing burring issues from the get-go, leaving edges needing little, if any, stropping afterward.
For edge angle, I NEVER use anything wider than 30° inclusive. And the 'sweet spot' for all my knives is narrower than that, at around 25° inclusive, no matter the steel type. I have a few that have been taken narrower, to somewhere between 20° - 25° inclusive. For some very specific uses, they're great cutters - but they start to become more vulnerable to edge damage at angles below 25° inclusive. So I tend to 'baby' those edges a bit. The upside to these thin edges is, they will tune up very easily on a bare strop, if/when the edge rolls a bit.
