The things I would like:
- default to private mode
- store bookmarks with choice of container - really weakens the feature when I can't e.g. bookmark two different gmail accounts
- built-in vertical tabs - extensions just can't achieve perfect UX e.g. can't tear out tabs to move to different windows, poor use of space due to side-panel header, keyboard shortcuts etc.
- Firefox IOS - lots of rough edges e.g. like always trying to autocomplete my urls to the worst possible sites that I never willingly visit e.g. outbrain, guice, oath etc. and no way to remove them
- better debugger and dev tools - still not a patch on chrome dev tools sadly
- become the better choice for Electron style apps (smaller, faster, easier)
- become the better choice for headless testing