I bought my Mark III Hunter used and it came with a set of Altimont grips. I like them a lot and they fit my hand pretty well. I did change them out for a set of Volquartsen Rubber grips and shot them for a few months but thought they were oversized for my hand.
I recently bought a pair of Herrett Stocks. They are a lot thinner and have a thumb rest which I like over the stock Ruger Grips.
What do you like on your Mark III?