Safari supports extensions, too, but Chrome has a much bigger selection. Chrome, however, runs everywhere: Mac, Windows, iOS, Android, Linux, and more. Apple used to offer Safari for Windows but discontinued that version in 2012. In those situations, you might have better luck with Chrome. If you're a heavy user of Google services, Chrome is the simplest and best-integrated way to access them.
Chrome ties into the Google ecosystem: You can sign in to your Google account using Chrome and use all the services and data in your Google account, right there in your browser.
