Can't really nominate any canon unit, my "go to"s are always custom jobs to begin with. It's just not the same if it's a machine designed by somebody else.
That said, I do rather like putting autocannons of all stripes on them purely because dakka (note to self, you've not done enough with HVACs yet). I just don't do it in multiples all that often unless I'm either (a) explicitly modding an already existing multi-AC design and running with the theme or else (b) outfitting a slow assault chassis; most anything lighter, faster, and original gets at most one autocannon (of any type and caliber) to go with its other weapons because diminishing returns tend to set in too quickly after that.
