If the book contains lots of equations, ePub is not the best. The best thing I've found is https://github.com/softcover/softcover which can generate pretty decent ePub/mobi with math as images, but still not as good as latex-produced PDF.

The problem is, every single .epub reader renders things slightly differently so when you tweak your ePub to make it look good on device A, it ends up looking bad on device B. The fixed layout of PDF is certainly restrictive, but at least it's consistent.

Context: working for past year on producing a decent quality ePub for some equation-heavy books.