This is such a fun thread!
Just tried a bunch of Collings in a local guitar store... Made some new observations:
Build Construction:
Collings look very cleanly built. But IMHO the seemingly 'perfect' construction make them look too 'manufactured'. Santa Cruz don't look as cleanly and as perfectly built, which actually make them look & feel more like hand-built guitars, and overall just feel more luxurious. Just my opinion & taste anyway.
Rosewood Sound:
Rosewood Collings sound more fundamental, while rosewood Santa Cruz sound more lush with lots of overtones. I feel the tonal difference between rosewood Collings vs. mahogany Collings is quite subtle.
Overall Sound:
My earlier observations were further confirmed. Collings is all about power, clarity, volume. This is especially true in adi-top Collings. Those adi top can really blow your socks off. In a way, it's like embodiment of the quintessential Texas characters
Like they say, everything is bigger in Texas. Santa Cruz doesnt sound quite as 'in your face'; but I feel SC sounds more expressive, subtly beautiful and rich, more soulful... Not to say one is better than the other, they are just different.
The usual disclaimer: just my opinion & taste anyway...