Computer monitors can be best to read articles if the background is of a dark colour and the font of a bright colour, e.g.: my blog, i have used dark and orange design for readers to avoid eye pain or stress. But to read on a monitor it is really hard.
Compared to paper, it should be of a bright background and dark fonts. To learn more about these things, HCI can help you out on Google.
Hope one day everyone will have an ePaper to read all files in .pdf, .txt, .doc, .tiff, .jpeg, etc.. It would have been great. No need to carry heavy books and other files.