In Firefox Developer Edition Desktop, I was able to

  - Quickly change search engine clicking magnifier icon top right
  - Set a custom search engine keyword ("wiki" + search term in the URL) via right-clicking a search bar
  - View download speed of an ISO file
  - Zoom images in and out, both as part of a page and as a standalone file

I was not able to right-click > open image in same tab, or have different default engines in URL vs search bar. That last use case is really edge, considering they have a search bar with multiple search engines and one can set search keywords and for most people, having different engines per bar would be unexpected and confusing.