Its only killer feature to me is that websites are designed and tested with a Chromium-first attitude. As a regular FF user I might stumble upon a website that’s quite buggy or straight up doesn’t work, which forces me to use Chrome for that specific website. Other than that I don’t really feel like there’s anything, and Edge is currently a better Chrome than Chrome anyway.
EDIT: and for the record, I’m still upset Microsoft didn’t choose FF and willingly increased Google’s grasp
I've been an FF user and developer of many frontends for years and the amount of times I run into serious differences between browsers is somewhere near zero.
I've been on team FF since the switch from IE like 20 years ago- I agree sometimes there is additional jank, but I also want to add that it is rare enough that it's been a non-issue 99.9% of the time.
Even then, I expect some of it is the fact I use an obscene number of plug-ins to break most social media sites (to prevent overuse).
I built an extension[1] so that I could choose which sites are opened in Chrome... so that whenever I need to use Google Meet, it automatically opens it on Chrome.
EDIT: and for the record, I’m still upset Microsoft didn’t choose FF and willingly increased Google’s grasp