This is the only Swiss Army knife I have. My grandmother brought it back from Switzerland in the early 1950's and gave it to my dad. He gave it to me when I was around ten...about 1958.
I don't own one of the modern ones, so I really can't give an honest opinion about them.
I
do, however, own several Case knives.
Since the Zippo lighter company took Case over in 1993, the quality of Case knives has improved significantly. From what I understand, they brought some of the old Case metallurgists out of retirement in order to bring the quality of Case knives back to where they once were. The Case knives of the 50's and 60's were top notch. It wasn't until the 80's when their quality started to slip.
I really like the quality of Case steel, particularly their chrome vanadium (high carbon) blades. Their stainless blades (what they refer to as "surgical stainless") are very good, too, although they take a little longer to sharpen.
Now, remember, the only SAK I have to compare the Case knives to is the one that my dad gave me. Between that one and the Case knives that I own, the Case knives win hands down. Better steel, better edge retention, easier to sharpen, etc.
Of course, that's just my two cents worth.