There are browser extensions for selecting links. It used to be called Select Like A Boss, now it's Drag-Select Link Text. tl;dr: drag horizontally to select text, drag vertically to drag-and-drop as usual, press and hold to select the whole link text.
Is there an about:config option toggle for this in Firefox? Seems like the kind of thing that should be an option in there, given everything else you can adjust, and it seems a bit much to have to need a full on browser add-on to be able to do this.
