The Good Housekeeping Institute states that, as of 2015, the best lightweight vacuum is the Oreck Magnesium RS. This vacuum features a slim style and has proven power in picking up debris from both carpet and hard floors.
Allergy Buyers Club prefers a different model and brand as the top lightweight vacuum, the Miele S6270. This vacuum features a quiet motor and Miele's specialized filtration system.
The Smart Review website offers yet another recommendation, the Hoover Platinum UH30010COM. The preference is based on a large number of positive Amazon.com reviews, many of which cite technology reducing blowback of vacuumed material.