I'd read in woodworking mags that the Shapton's were excellent. Shapton would certainly seem to be serious about stones, given they offer a #15000 ($120) and a #30000 stone ($595!). Those are extremely fine grit stones. Assuming the grit rating is similar to my water stones, #8000 puts a near mirror, superduper hair jumpin edge on my wood hand planer blade.
Norton's synthetic water stones are quite good also... they cut very fast (faster than Arkansas or India stones)... IF you are willing to put up with the water stone's propensity to dish out (you have to flatten them once in a while with, e.g., a nice flat and coarser diamond stone.)
(to be clear, fine grits put a seriously polished edge on a knife... that isn't always what I want, so I usually leave my working knives a bit toothy with a DMT fine diamond stone. Refined and polished DOES help with wood hand planers, however...cuts wood grain more cleanly).