[kbr2000]

Reminds me mostly of LyX [0], although that one does use LaTeX and Tex; and targets a WYSIWYM approach [1]

[0] https://www.lyx.org/

[1] https://en.wikipedia.org/wiki/WYSIWYM

[nxobject]

I've used LyX for a very long time. It has the best graphical equation editor I've ever used: it natively supports all of the complex structures you'd want, can be used incredibly efficiently via the keyboard (e.g. tab-completion and tab-navigation), and is still incredibly discoverable via GUI.

In general, it's just a very pragmatic layer on top of LaTeX. I've done a lot of complex ad-hoc formatting in it as well.

[zelphirkalt]

I like, that one can define macros in LyX. For example I wrote a simple macro that looks like "paren(thing)" which is then translated to "\left(" thing "\right)". This makes it much easier to write formulas, because I don't have to keep track of parens at all. LyX in this way makes it more convenient to write TeX/LaTeX.

[GiovanniP]

Superior to LyX: fully WYSIWYG, no limitation on what it can do.

[nxobject]

On the other hand, you do get the full (La)TeX ecosystem to draw on. If I want to draw a commutative diagram, I can add tikzcd to the preamble, and insert inline TeX to do so.