I guess i will do two in one because i've just changed about three years ago.
The first i used were Gesswein that i got out of a gunsmith catalog, then from Gesswein directly, which included an Arkansas hard bench stone, and a ruby Medium (only used for nicks) and fine Ruby stone. All worked very well and i really can't say anything bad because they lasted several years with the ruby being an awesome finish/hone stone.
But these really don't work (nor do/will your basic stones) on most Japanese or "thinner" bladed knives, which i started to use aprox. 3 years ago and found out the hard way.
So, in looking for new wet stones, my wifes uncle directed me to this place he orders woodworking tools from, out in California, i gave them a call and orderes a catalog. http://www.japanwoodworker.com/page.asp?content_id=2896
Unbeknownst to me, they not only sell woodworking tools and sharpening stones.......They also deal in handmade kitchen knives, graters, and much more!
So, in looking in the catalog 5 days after i called, and went ahead and ordered their Shapton Professional water stones, in all grits (grit range from 120 to 30,000).
I can honestly say, after using these, there has been a significant difference in edge sharpness and retention! While using the coarser grits for heavier bladed knives and other metal finishing work, i can't say i'd ever use a different set of stones because they last first off, and secondly, the edge it gives is even more horrifying than scary sharp!!!!
Since then i have ordered many more things from them, and give that company 100% customer loyality and satisfaction!