[reaperducer]

The thing that keeps me from using Firefox is that it doesn't use certain standard macOS interface methods.

That keeps me from using macOS's built-in keybinding system to change tabs with the touch of a function key.

Every other program I use from Finder to my database manager allows me to switch tabs with one button. Firefox has no way to accomplish this, which would make it an interruption to my muscle memory and therefore my productivity.

Duck allows it, so that's what I use instead of Chrome.

[krackers]

There's a way to rebind keys in Firefox, but it's extremely convoluted: something about editing omni.ja. I feel like Firefox goes out of its way to make it impossible for you to do so. Not to mention that they also go out of their way to be hostile to extension developers (unlike Chrome where you can just load an unpacked extension, with Firefox they impose the arbitrary limit that it gets removed after a restart).

Also they don't seem to care one bit about user experience (in the genuine sense). There's a long-standing bug open for > 10yrs that Firefox does not disable sleep when uploading or downloading files. The day that I started a long-running downloaded and came back to find that my laptop had gone to sleep before it even hit 5% was when I uninstalled Firefox in a rage.

[jlokier]

I'm not sure if this fits what you want with "allows me to switch tabs with one button", but in macOS Firefox keys ⌘1 to ⌘9 (cmd-1 to cmd-9) switch to tabs 1 to 9 respectively in the current window. ⌥⌘← and ⌥⌘→ (alt-cmd-left and alt-cmd-right) switch to tabs left/right.

[reaperducer]

That's two buttons, and different from how every single other program in my computer is configured, which is why I use Duck, instead.