depends
It really depends on what you want to use it for and which of the applications you are referring to:
I found numbers to be pretty bad compared to excel.
Pages does a good job with formatting and layout, it is very easy to use and you can directly export every page as is to PDF, which I find a very usefull feature. However, it does not include cross-referencing which makes it a bad choice if you are writing something scientific.
Keynote for me is far better than PowerPoint as here the way it looks and animations are created are the key issues.
Best
Nase