All the fixups, for five: browser.fixup.alternate.* (multiple) browser.fixup.dns_first_for_single_words browser.fixup.fallback-to-https (If I type something in the url bar I damn well mean it! It'd be fine if it tried others, but it tries them and then stays on them, meaning I have to retype urls to get it to load the actual thing I want.) There's a few others that I don't _need_ but do use that I'm not including here.

System-provided custom CAs, for another, and removing the CAs I don't trust and am not likely to be impacted by removing. I don't need or want trust in a Turkish CA, for example. Cert stuff in particular gets worse every year, and here's another specific example of that: security.certerrors.permanentOverride. Enough said, I hope. At least they give me the option to make it temporary again.

There's no GPSD support in any easily available Firefox: https://bugzilla.mozilla.org/show_bug.cgi?id=1250922#c24 and they're going to remove it (again) because they didn't maintain it: https://bugzilla.mozilla.org/show_bug.cgi?id=1803234. Now I need dbus and geoclue, I guess. Where are the docs on how? I think it's clear enough that Firefox is not being made for the _users_ with this topic.

There are more, but I hope this is enough to show that they exist. These are the most egregious, for me - if they were removed I would stop using the web entirely the same way I've stopped using my cell phone for everything except work.

findbar.highlightall is essential for me

extensions.pocket.enabled

hide "are you sure" dialog when opening about:config

browser.urlbar.clickselectsall (now defunct)

extensions.checkCompatibility & friends (not sure if still necessary since I can't recall why I'm using it in the first place)

browser.backspace_action (might be platform dependent?)

browser.tabs.tabMinWidth

browser.compactmode.show

user.js customization because when I use tree style tabs there's redundant UI elements