This has been an interesting thread to read. I appears that many are confusing HRC with the grade of steel. Or more importantly not using both to factor the quality of the blade. In very general terms, a high carbon, high HRC blade will hold the best edge. However you will have a blade that will be very brital. The key to any good knife is finding the balace between carbon content and HRC. The best all around blade in my opinion is a damascus blade. Especially one with a high carbon insert for the edge. This allows you to take advantage of the best aspects of several types of steel, while still maintaining a very sharp edge. Here's a great resource for some futher reading:
http://zknives.com/knives/articles/index.shtml