Hi MISST,
Welcome to Digicamhelp!
The best way to tell what camera is best is to take photos with each and compare. Both Olympus and FujiFilm make fine cameras. You may also want to do a Google search and find some reviews of what others are saying about each.
As to the best megapixels to have, that depends primarily on two things. First, how large prints do you plan to make? If not more than 4x6," then a two megapixel camera is fine.
The other thing is if you do a lot of image editing. If you crop you images a lot, more megapixels mean you can crop more without losing image quality.
Since the Oly is a four megapixel camera, and the FujiFilm is a 2 megapixel camera, obviously the Oly will give you more printing and editing options.
We have it all explained here:
http://www.digicamhelp.com/what-is-a-megapixel/index.htmAlso check out this page which suggests how many megapixels you need for a particular size print:
http://www.digicamhelp.com/what-is-a-megapixel/megapixels-and-print-size.htm