Originally Posted by funkypunkypinkypow
okay, But I just want to high compress my files to backup on Internet
Ok, you didn't state that, you simply said "upload to internet"
without any further information most people will assume that you're doing this because you want to share the files.
If you're talking about for your own backup then there's also no simple one-utility-fits-all answer. A lot depends on your PDFs.
A quick Google (you did do that first yeah?) gives http://www.techradar.com/news/softwa...-tested-933098
So take the latest versions of those 8, make your own test suite of representative PDF files and see which gives you the best compression.