If you're aiming for particle purification, you should look into buying a device with a HEPA filter. These are ideal for catching fine airborne contaminants.
As opposed to activated carbon, which is only suitable for gaseous molecules, HEPA filters can also trap solid particles. In this way, they help clean the air and eliminate odors.
Air purifiers aren't cheap, and you obviously want the unit you buy to last at least a few years. Always prefer products that are durable and long-lasting.
Be sure to read through customer reviews to get an accurate picture of how long the unit has lasted for most users.
Some air purifiers are easier to use than others. Some units have a sole on/off button, while others may include remote controls with many complex options. If you want a product that is easy to use, stay away from remote-controlled air purifiers.
Such devices can be confusing, especially if you're in a hurry. However, they offer more customization options than units with an on/off switch. Which option you choose ultimately depends on what level of simplicity (or complexity) you're comfortable with.