What is the best font for readibility and economy (=maximum number of characters per page) given following specifications:
-page size A4 with 8 mm margins on left and right and 12 mm top and bottom
-assuming a page with just text, the font should give a total of 11500-12000 characters per page (including spaces)
-either 3 or 4 columns with a 3 mm separation between each column
-should be readable under suboptimal lighting conditions.
This is just for hobby without any professional or commercial pursuits. I managed to get about 11500 characters on an A4-page by using 0.9 line spacing and Adobe Jenson Pro Semibold 9pt and 3 columns. That with just MS Word.
Readability and legibility are subjective and depend on many different variables that one must consider. Readability can’t be reduced to a simple conclusion of one choice always being better than another. In other words, your question presupposes an answer when there is no definitive answer.