Kindle is not the only ereader to have an eink screen, in fact every device that is marketed as ereader (and not i.e. a more generic tablet) uses this technology.
Said that, basically every ereader available today can do the things that you need; I think that the real choice when speaking about scientific books that contain math and formulas is about the ebook format, not about the ereader: reflowable text formats like Amazon's .azw
and everyone else's .epub
can get the job done, but maybe for some more complex layouts, a fixed page format like .pdf
could be a better choice. It really depends on the specific book and how well is formatted.
Choosing an ereader and a brand is more a choice of an ecosystem rather than about differences in the hardware (all of them, more or less, are equivalent and have the same features); Amazon Kindle is maybe the more closed platform, meaning that it uses its own file formats, while the rest of the world uses the de facto standard .epub
.
You can also try to have a look at these questions: