Throughout our thorough reviews process, we consistently find that a vacuum's power rating has little impact on suction. Instead, a combination of factors, including motor and cylinder design, whether the bag or bin is full, whether the filters are regularly cleaned and the shape of the vacuum head can all affect how good a vacuum cleaner is at its job. The 1,400w AEG Ultracaptic Animal has the most powerful suction of all the vacuums we've tested to date, outperforming 2,200w machines.
A wattage rating isn't always an indicator of what's being drawn from the plug socket, either; we've seen 2,200W rated vacuums draw less than 1,100w, and 1,000w cleaners exceed their rating by up to 200w. Power draw will depend on the power setting and suction mode of a cleaner, if it has them, as well as motor wattage.