Why FireFox?
Same reason I choose any program.
1) Does it do what I want ? Browse the Web
2) Is It intuitive to use ? Same UI design as most of my other programs
3) Can I customize\tailor it to suit me. across muliple devices? Book mark Sync
Firefox does all these, Chrome is Pig Ugly, IE\Edge don't have the extensions.A.N others are too niche to invest the time in.
Is Firefox perfect Hell No! It eats memory bitches at some sites and occasionally needs re-tweeking to undo the latest developer 'masterpiece' innovations. But for me it's the best option.