I actually prefer ebook for both - including for studying. If the book I want to study requires larger screen, I prefer notebook. I never wrote into books, if I am taking notes it is on paper and sometimes electronically (with keyboard).
For comparing tables, I prefer laptop.
> What ereader do you use?
Fbreader, nothing special.
> How are you taking notes (that you would be able to retrieve later in a reasonable manner), using the index, etc?
It has bookmarks I occasionally use.
I write actual notes either with pen&paper or keyboard into a file on laptop. Retrieval is via ctrl+f or looking at the paper.
> I actually prefer ebook for both - including for studying.
Really?? What ereader do you use? How are you taking notes (that you would be able to retrieve later in a reasonable manner), using the index, etc? I've wanted for years to switch to electronic books for nonfiction that I want to learn from, but software for reading feels so bad for this purpose.