There are many CPAP (continuous positive airway pressure) machines on the market, and it can be difficult to determine which is the most popular. Some of the most well-known and respected brands of CPAP machines include ResMed, Philips Respironics, and Fisher & Paykel. It's important to note that the best CPAP machine for you may not be the most popular, as different machines are designed to meet different needs and preferences. It's a good idea to speak with a healthcare professional or do research online to find the best machine for you.