I break up the dizzying array of SAKs into 3 categories by size:
a) small enough to fit on a key chain or watch pocket
b) just right for pocket carry
c) so big that they need to go on your belt or in your pack.
In the first category, I would restrict my attention to the ALOX scales, especially if you are carrying on key chain. I never got more than 2 years of use from Classics on my key chain and have never worn out a Leatherman Micra. Actually... my recommendation in this category is to just get a Micra. I carry mine in my LFP to augment a folding knife (normally an Opinel).
EDC Pair by
Pinnah, on Flickr
In the "too big for pocket carry" category, again, I prefer a Leatherman style multi-tool. SAKs in that size range just don't appeal to me. For me, 3 layers is when I start to find the SAK's too thick and heavy, depending on the knife.
ATMO, SAKs hit their sweet spot in the classic camper sized range. Which set of tools you carry depends a lot on your lifestyle. I like having the tools on my Micra and would seek to replicate them. Scissors for me are a must and I have no need for corkscrews and can openers. The only right answer here is what works best for you.