Andrew Gabriel wrote:

That's what "suction power" is -- the vacuum pressure multiplied by
the air flow. Neither the vacuum nor the airflow are meaningful by
themselves -- a vacuum pump and a large desk fan would have better
individual ratings than a vacuum cleaner, but are useless at cleaning
floors.

In practice you cant have vacuum pressure and airflow at the same time.

In actual application it's airflow that's important, not vacuum and this
varies with the 'final aperture' size. Essentially a 32mm hose gives more
suction/less airflow than a 36mm hose. Using two motors in parrallel leaves
the suction the same but nearly doubles airflow - which is why twin motor
vacs pick up better.

Vacuum pumps are actually used to clean floors - some American manufacturers
of carpet cleaning machines, usually truck mounted, use vacuum pumps rather
than vacuum turbines to achieve better water recovery rates

Combine this with the maximum size of particulate at the air exit and
the mass of dust retained by the machine and you don't need anything
else to know what's better.

Depends on the filter and if it can easily be cleaned or not.

Dave