There isn't a best vacuum. It's all about what matches your requirements. For example a kirby vacuum is VERY powerful at cleaning carpets and has a ton of airflow. It can do anything other vacuums can do and more, such as being a carpet shampooer and blower for example. This is what loads of Americans swear as being the best vacuum.
However, others may argue they are heavy, bulky, loud, a pain in the ass to use and outdated along with looking vintage. They could also say a Dyson is better because they have better hose suction, are quieter, are bagless (bagged vs bagless is another debate), have a way more sophisticated, convenient design, look better and have better filtration.
Many Brits also swear that Henry vacuums are the best because they are indestructible, can suck up anything from fine dust, to large clumps of tissue, rubble, *anything that fits through the hose*, are quiet, don't use a high wattage, never lose suction, have a huge bag capacity, the list goes on.
In contract, others may say Henry stinks due to dust and dirt festering and rotting in the fabricated bag which absorbs the odour so you'll have to change the bag regardless of how empty/full it is, it doesn't clean carpets properly, it's top heavy and falls over, etc.
So TBH it's trial and error, try whatever you like, don't always listen to other people's opinions on the best vacuum, because everyone is different.
The moral: Try out different machines and form your own opinion