You mean OS as in "operating system", not "open source", which made me question how you'd suggest Safari and Edge before I realized what was going on.
I don't know why using the default browser a OS comes with or not would be better? Who cares? All that matters for me is what features it has and that performance isn't horrible, and if I cannot have vertical tree-style tabs in it and hide the tab-bar, then I personally have no use for it. So stuck with Firefox I am, and been for decades.
Besides, if my OS is Arch Linux, what browser is my "OS-browser" anyway?
I don't know why using the default browser a OS comes with or not would be better? Who cares? All that matters for me is what features it has and that performance isn't horrible, and if I cannot have vertical tree-style tabs in it and hide the tab-bar, then I personally have no use for it. So stuck with Firefox I am, and been for decades.
Besides, if my OS is Arch Linux, what browser is my "OS-browser" anyway?