What's the best adhesive for affixing quartz countertops to a bathroom vanity?

Specialty Trades Masonry
2

Silicon

3

A decent silicone or construction adhesive that stays plyable such as np1 from 3M.

4

Countertops are usually installed with liquid nail but silicone or rubber cement does the trick as well.

5

100% clear silicone bead around the perimeter of the cabinet top. CRL makes the best and GE’s isn’t bad either.
Jeff