Well, choosing the "best" Export/Share setting for output, is a bit science, a bit art, and often a bit of testing.
File Size rests primarily on Bit-Rate, which roughly is = to "quality," and then the Project's/Sequence's Timeline Duration. It can become a delicate balancing act between quality vs file size. The amount of motion, especially off-axis motion, would be where to look for ultimate qualtiy, established by Bit-Rate. Lower motion footage, will still look good,at a lower Bit-Rate, but only the editor, or the client, can make the final determination.
For some general discussion, see this Adobe FAQ Entry.
Note: the above is focused on Premiere Pro, but most applies directly to PrElements, as well. However, the term for Export is now in PrE's Share Tab, while Export is the term used for either direct output,or output through AME (Adobe Media Encoder).
Hope that helps one determine the best output setting for their material.