Many people swear by the syderco sharp maker. Great little system that will sharpen just about anything.
If you're like me and enjoy free hand (stones) AND never let your knives get too dull, the very basic system I have is:
a medium/fine diamond stone
a 2000/5000 corundom whetstone (water)
A ceramic honing rod
A leather strop & compound
The diamonds will handle any harder steels down to a pretty decent edge
With a good edge already established the whetstone will have no trouble final buffing out the scratches, and the stone will work fine by itself on your softer steels that the diamonds are too rough for and will chew up (the fine diamond works great on bring an edge back on really dull softer steels)
Regular honing (more for kitchen knives) and stropping (more for the pocket knives) keeps them sharp so you don't ever need the really coarse stones with proper maintenance... And coarser/finer stones can be added as you go, but those basics will handle a shaving sharp edge on any blade I've encountered, though I'll admit I've never tried m390 or s90v, but 154cm, d2, s30v have all been no problem
And I keep a few smith pocket pals and coarse/fine mini diamonds (1"x4") around in the car, back pack, etc in case I'm ever in a jam and need to bring a quick working edgevto life.