I'm not sure this approach would help a lot of people, especially if they ended up choosing to buy a particular Alchemy library because it had more multi-sampled SFZ files than others - this won't tell you how 'good' or 'bad' a library is.
In general, SFZ files mapping multiple samples are used when sounds change a lot across the keyboard, such as human voices and acoustic instruments, so there is for instance lots of SFZ content in our Dream Voices, Analogica, Himalaya: Vintage among various others
However, much of the character of created sounds can come from layering using single samples at extreme engine settings. Moreover, many of the other Alchemy libraries (including my own Steamworx) contain lots of SFZ files not only for more realistic acoustic instruments but also for drum kits, assorted percussion, complex looped instruments...
Martins right that the number of SFZs doesn't necessarily indicate the quality of library as there are so many other factors. But I can see that some people such as yourself may be especially interested in SFZ files for some reason. At the moment, we don't have a list anywhere of the number of SFZs in each library, but if there's demand we'll consider adding it to the product page. Here's a few ones I just looked up for you which I suspect are amongst the highest, if not the highest in terms of SFZ files:
Shlomo - 156 SFZs
Dream Voices - 113 SFZs
Guitar Mutations - 91 SFZs