MS Office isn't availabe on either platform.  With Android you can use Office Suite Pro to work with excel files.  I have it but use it to just view files, so can't help with how it works to add data to.  I vote for the Galaxy S4, I went to an S3 from an iPhone 4s.  The main reason I went with it is because of screen size.  It was much easier to read than the iPhone.The new S4 had an even bigger screen so it should be easier to read than the S3.  As for as app availibility most ag apps are on both platforms.