-"X moved Y pixels making Firefox UNUSABLE! So now I use Brave."
-"Mozilla is run by a bunch of SJW idiots because they ran their CEO off. So now I run Brave." (I had to look into this, as I wasn't paying attention at the time. They picked a new CEO who cared so passionately about removing the right of gay people to get married he even donated his own money to the cause. That was a dumb hill to die on. Now he's an anti-masker who actually runs Brave.)
-"My precious browser workflow was completely dependent on the interaction of 156 distinct XUL extensions so now I use Brave."
-"something, something, Mr. Robot." (that, like everything, you can turn off)
-"Ads in the address bar!" (that, like everything, you can turn off)
-"They take money from Google!" (Hey, free money, since everyone either switches to DGG or were going to use Google anyway.)
There are real criticisms you can make of Firefox/Mozilla. But on the whole, for the general user, none of them are grounds for moving to a Chromium based browser out of spite.