Archaic as I am, I want to put in a word for WordPerfect’s “old” equation editor, dating back to its DOS days. It can still be found in modern releases, but you have to dig into the graphics settings to change the defaults, and there is no documentation for it. (I had to buy a 20 year old or so used manual online; I’ll be happy to send a scan to anyone who needs the section on equations.)
What makes it valuable is that it’s completely text-based, as befits a DOS-era program. It incorporates a much more extensive and finely-tuned set of formatting tools than object-based alternatives, and it’s a wonder for copy-and-paste jobs like big matrices or equation sequences with repeating expressions.
The chief drawbacks are (1) equations are lost in export to Word and (2) they are bolded and rather ugly in export to pdf. Using cropped screen grabs is a possibility, but it means that the resulting document is not editable; this is also problematic for inline equations. These don’t bother me so much for the type of writing I do—I never publish in journals but only in books, reports, PowerPoints, etc.—but I can understand why it would be a deal-breaker for most academic economists.
ps: The spell-checker doesn't recognize "WordPerfect"!