They are mostly the same. I think they look better on Firefox.

Firefox has no websockets inspector which chrome has but it does have a CSS grid view tool which chrome doesn't have. There was a bunch of new improvements to the Firefox dev tools recently but I haven't checked them out yet.

Not advocating browsers either way, but as someone working a lot with css grids lately, chrome does have this tool. Hovering over any element that has a grid-area style, or a grid-template-* style will display the full grid on the page.

If you do a lot of debugging or reverse-engineering, FF’s dev tools lacks a lot of essential tooling compared to Chrome.

Things like getting all event listeners for a DOM element (with inspectable closure variable values), local workspaces, blackboxing files and folders, async-spanning stack traces, saving CSS/JS edits to source files, document event breakpoints...

You could even consider using more than one browser... one for dev tools, one for everything else.

If you're developing for the web you'll need to use more than one anyway, because you'll need to know what your site looks like in Chrome.