As others have stated, it's difficult to quantify "better". For instance, and this is simply what I've heard rather than from personal experience, SR77 will rust readily, but the corrosion remains a surface issue -- it doesn't pit. SR101 may actually resist corrosion a bit better, but I've heard that when it does rust, the corrosion penetrates, resulting in pitting. I've also read that INFI was not designed to be stainless, but in practice, it's very corrosion resistant (if I had to guess, it would be due to Nitrogen content, like Spyderco's H-1 or Boker's X15).

As to both toughness and edge retention, the steel has a lot to do with it, but the tempering process is actually the number 1 factor. You can enhance the performance of poor steel with good tempering (at least up to a point) or absolutely ruin a good steel blade with bad tempering. That, more than anything else in my opinion, is the the key to the Busse (family) knives success. They start with good steel, although some other knives are made of almost the same material, but they use a superior tempering process.