Chrome seems to currently hold the record of being the de-facto standard for web browsers. It’s fast and secure, and tends to support the latest technologies and advancements in web technology sooner than most other browsers. In addition, its automatic and seamless updates prevent most users from falling behind on updates (as has happened with IE users).
With that said, I’d probably say Firefox comes just behind Chrome, being open source and a bit lighter-weight than Chrome (which tends to hog a lot of RAM, esp. on older / slower computers). In addition, as a developer, I’m occasionally forced to switch to Firefox to test certain things / load some interactive webpages, as Chrome has been clamping down on security, and disabling many features for non-secure / https sites, thus breaking many previously working interactive web apps and games.