Years ago, we didn't have the luxury of being able to decide whether we wanted a lightweight vacuum cleaner. A vacuum cleaner was a vacuum cleaner so the possibility of a lightweight vacuum cleaner was inconceivable.
These days however, lightweight vacuum cleaners are immensely popular and there are several reasons behind this surging demand.
If you have a large house to vacuum, or would like to vacuum the stairs in one go, make sure your new vacuum has enough hose and lead length. It's rather frustrating when your vacuum won't quite reach into the corner and you have to go back to the power point and replug into another one.
A high wattage (input power) doesn't always mean better suction because the amount of this power that's turned into air watts (suction or output power) depends to some extent on the vacuum's design and efficiency.