I wrote my PhD in TeXmacs: https://www.texmacs.org

Advantages:

- It's the fastest environment for me to type mathematical manuscripts.

- If you are familiar with LaTeX, you can backlash your way in immediately.

- If you are familiar with Word, you can use the dropdowns as you would use the Equation editor.

- The typesetting is great.

- It has great LaTeX export (there are a few things to clean up, but that time is in the single percent digits compared to the time savings).

- It has .bib support for citations.

(Working with exported LaTeX code seems ugly, because of the pretty-printing though)

Disadvantages:

- It crashes. Nowadays much less, but that's still a hassle. Splitting your work in multiple files helps (especially for a PhD-sized document).

- Five years ago, it was difficult for me to figure out how to use macros, customize the layout, so I mostly gave up. If you have to automate a lot of custom type-setting, LaTeX is probably still king. I haven't skimmed through the new book, I would do it if you plan to use TeXmacs: https://www.scypress.com/book_info.html

- Fiddling with bibliography formatting wasn't fun, it is not fun either with LaTeX, but LaTeX often has a StackOverflow answer for you.

I'd give it a try, absolutely. You'll need to decide pretty quickly if you want your workflow to go TeXmacs->LaTeX->PDF or TeXmacs->PDF.

In the first case, you'll process the pain points in LaTeX, but there'll be people around you to help you.

In the second case, you'll have to dig into TeXmacs styles if the default options do not suit you.

I also use TeXmacs to prepare slides, because that's the most efficient workflow I have. Though I have to route my intent around the software limitations, I find it quite worth it.