Unfortunately none of the formats given work with Amazon's "email to kindle" system, which is the most convenient way to load books-- it allows you to download a PDF on your phone and send it to a special email address associated with your Kindle device. Considering all the work this site has already done preparing the book files, it seems like they might as well ought to generate PDF files using a page size roughly equal to that of the most common Kindle readers.
Amazon's "email to kindle" system also accepts books in the mobi format which would be a preferable to mapping pdf page sizes to Kindle reader screen sizes.