This is a very common question without an easy answer. Choosing the right vacuum depends on a few different variables. Start by answering the following;
What type of flooring do you have? All hard surface or a mixture with wall to wall carpeting
What type of carpeting? Low pile or thick and dense pile, thick pile carpets require a height adjustable power nozzle
Do you have pets? May want to consider a charcoal filter system
Do you have stairs? Canister vacuums ar far better suited for stairs
What kind of filtration do you need? Hepa or Basic
By answering these questions you can start to narrow down which vacuum is right for you.