I would also vote for Spegels, but keep in mind his wait list is about a year, maybe more by now.
Ahrends are a good choice. As gwpercle said, the solid wood options are best. The Ahrends grips I had came with the tung oil finish, which I highly recommend. It's smooth, so it won't catch on your cover garment, if you're going to carry concealed, but when you get it in hand it's non-slip.
You might also want to check out Eagle Grips. I have an older set of their Secret Service boot grips for my 642, and I like them. I haven't tried them on a K-frame, though. Eagle has other options if you prefer another style of grips.
Herretts are a good option if you want a true custom grip. You send them a tracing of your hand and they'll shape the grips specifically for your hand. I don't have any experience with their revolver grips, but they come highly recommended. Can be pricey, though. It's been a while, but the last time I looked their custom revolver grips were well north of $100.
I don't have any experience with Culina's, but they're highly recommended and every grip I've seen from them has been beautifully crafted.
I have no experience with them, but BluMagnum Grips look great, albeit pricey. I'm sure they're worth the price, though. I'm rather partial to their Skeeter Skelton-style grips.