I use them all, because I have a 1TB Samsung SSD with the Xen hypervisor running on it, which means I can dedicate whole operating systems to specific browsers. Each browser has its own 'unique selling point' and I use each browser according to my needs.

-Firefox for privacy

-Tor Browser Bundle for enhanced privacy

-Brave for micropayments

-Vivaldi for customization/tweaks and reading the news

-Chrome because it's ultra fast

-Microsoft Edge just because I can