What attachments will you use?
Some vacuums come with a great number of add-ons that you can use when cleaning, to get into the smaller nooks, crannies, and take care of different types of flooring. It depends what you want to use the vacuum for in your house.
For example, when cleaning air-conditioning and heating vents or vacuuming the areas under the pieces of furniture, you will need a crevice tool (an angled hose attachment that works well for corners and small spaces.) If you're going to vacuum walls, you should get a wall brush. Curtains, mattresses, and upholstered fabrics like sofas or car seats should be cleaned with a special upholstery tool. So, check if the vacuum you're going to purchase comes with the attachments you need or you have to buy them separately.
It's important to note that most handheld vacuums don't come with as many external attachments as cannister vacuums, which are often "all in one" models.