I see and hear about many differences between Firefox and other browsers, mostly on user-facing features, but also some on technical level. They can be small, or big, depends on the user. Maybe your view is too technical to really see the user-impressions?
> I see and hear about many differences between Firefox and other browsers, (...)
Can you point out what you feel is the single most noticeable difference? I use Firefox as my daily driver but I also use Chrome, and I never noticed any difference.
It's not a single difference, and not something simple to point out. Because yes, at surface they are mostly the same. They mostly look similar, behave similar, Firefox is on surface just another browser like chrome. Which is the problem, because Firefox does not offer any features outside the core-ability of Web-Browsing.
Chrome on the other side has good integration into Googles ecosystem, has better support from Webapps (yes, this sometimes is a relevant topic), is depending on the platform significant faster, and seems to have some better side-features here and there. So its whole identity is to be THE Google-Browser, well polished for the modern World Wide Web.
Similar stuff is with Opera, Vivaldi, they all have their own special identity which they support with accompanying features. Like Vivaldi being an app-suite which offers more than just web browsing, or Opera with their Gaming-Browser catering to give gamers a good selling point. Not sure that Brave is doing today, but they were once strongly focused on AdBlock and earning Money?
Firefox on the other side has nothing of this. It once was the everything-browser, which could be anything through extensions. A mail-client, ftp-client, web-archiver, note-app, office suite, and much much more, all depending on the Users preferences. But that is lost, and now it can't even restore lost basic features. At this point it's just a window to render Web-stuff, with a better Adblocker and customization than Chrome. And even this is not advertised well. I mean the last ads I saw from Mozilla were not even about anything specific, just random pictures...
I don't use Firefox as my primary browser, but I do use the desktop version of it on various computers numerous times per week as part of some work I do.
I find Firefox to be noticeably slower than the various Blink-based browsers and Safari (when available) when running on the same systems. I'm referring to the overall responsiveness of the UI and the application itself, as well as the rendering of sites, and the subsequent interaction with them. I find this to be the case for a fresh installation with no extensions, all the way through to an installation with common ad blocker extensions installed. Firefox is just plain slower, from what I can tell.
Firefox's extension signing nonsense is another pain point. As part of my work, there's a fully-trusted custom extension developed in-house that I need to install. It's trivial to install in the various Blink-based browsers. On the stable releases of Firefox, though, I have to jump through numerous hoop to get it installed and usable, and this has to be done each time the browser restarts, which is often in my case.
