best cleaning vacs
In my humble opinion, and on a non-wall-to-wall carpet, you cannot beat the Hoover 150 for cleaning. With four beater bars (and two brush strips), the 150 beats the heck out of the rug, removing virtually all the sand and grit.
Next, I would say any Eureka with a Vibra-groomer 1 brush roller. Eureka had more airflow than Hoover's convertible series (and a better paper bag arrangement) which allowed the Eureka (F & G style) to deep clean rugs.
My royal PowerCast is an excellent carpet vacuum. Timeless design and wonderful performance, plus Hepa filtration.
My friend Derreck bought a $1200 Miele Capricorn S-5 and used it on his carpets in his brand new apartment several times. He used his old Eureka ESP (from 1980 - with VG2) on the carpet as a lark. You should have seen all the sand it got out that the Miele did not. I told Derreck 'it has to beat, as it sweeps, as it cleans' to REALLY get the rug clean. Miele doesn't beat. Eureka does. Eureka beat quarts of unwholesome sand and filth from his rugs in his new apartment.