Chrome is the "best" because all of the other browsers continue to fail at real world marketing. The best ads and marketing continue to be real life stuff - billboards, bus signage, people handing out flyers, etc etc etc. You can't just hype a browser on social media or web forums, and you can't hype it solely to those who are tech savvy.

A solid example of this right now is all of the Mullvad VPN ads I've seen on the Seattle Light Rail lately. Google used to have ads everywhere for Chrome. The only time I saw Firefox stuff was the rare t-shirt at a tech conference.