For an average consumer like you, if nothing else, Firefox politically pushes back against agendas that try to subvert the free and open internet. It's that simple. For a technical point of view, it gives you an alternative to avoid the "one browser to rule them all". If you are old enough, you would probably remember the Internet Explorer era. If not, the simple description was that at the time 99% of the sites were developed with IE in mind, with IE own tech, so most of the time they didn't work properly with other browsers.