Firefox is my main development browser on personal laptop (Ubuntu) and Chrome on the PC (Win10) at work.
When I develop (HTML, CSS, ES6+babel) on Chrome, then test in Firefox there are some inconsistencies that require minor fixing. The same is true the other way around: develop with Firefox, then some fixes are needed for Chrome. These fixes are usually quite easy, make sense in retrospect and make thigs work in the second browser without breaking the first one. What I find strange, after years of hacking around IE bugs, is that everything usually just works in MS Edge.