A vacuum cleaner is probably the most expensive cleaning tool you will buy so it's important when choosing your next vacuum cleaner to make the right decision.
If you're confused about the difference between cylinder and upright vacuum cleaners or the benefits of bagged and bag less vacuum cleaners, The Ultimate Guide to Buying Vacuum Cleaners will explain everything you need to know and much more.
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.
The capacity of the vacuum cleaner's dust bin or bag will essentially determine how often you'll need to empty it. If you have a large house and you don't want to be going back and forth the bin, it's worth investing in a vacuum cleaner with a bigger capacity. That said, if you have trouble lifting or manoeuvring a vacuum cleaner, bear in mind that the bigger the vacuum cleaner's capacity, the heavier it'll be.