Firefox
While Mozilla Firefox wasn’t the first open source web browser, it’s arguably the most successful. Still, Mozilla is struggling to compete against web giants like Microsoft and Google. Still, Firefox has managed to hang on to a 25% share of the worldwide browser market.
PROS: With about a zillion different add-ons, Firefox is by far the most customizable browser. That kind of comes with the open source territory. Firefox is known for being fairly secure and stable, even when you’ve got a lot of open tabs.
CONS: The same open source code that makes Firefox awesome, also makes it attractive to virus writers. It’s also a little bit slow, especially if you’re in a hurry.