I was a die hard Mastercook user for years, but I recently switched over to Living Cookbook. The problem with Mastercook is that Sierra, the company that orginally created Mastercook, sold it off to some other company, Valusoft I beleive. For a couple of years the company didn't do anything with it and when I went to Windows 7 I had to do some custom installing to even get the thing to work, and then half of the components didn't work as they should. Valusoft has now done an upgrade to Mastercook, releasing a new addition, but I just don't trust the company to continue to support Mastercook.
On the other hand, Living Cookbook, has a great support system, with the owner/programmer very active in the support forums to help people solve their issues. I have found it to do everything that I was asking of Mastercook so I've had no problems with it at all. I do have to admit that I am getting used to the look (I do like the Mastercook look better) but other than that I would have to suggest Living Cookbook.