LibreOffice is like your first car: it's ugly and barely runs, but it will get you from point a to point b most of the time.
MS Office is like a van: flexible, capable, powerful, large, overreaching unless you need to transport some clowns, but everyone of a certain maturity seems to have one.
"iWork" (the Apple combo of Pages, Numbers and Keynote): that sports car that is incredibly fun to drive, excels in a few areas, so zippy and cool, but Numbers has a rattle in it nobody seem to be able to fix.
Of the three I personally prefer Pages/Keynote (have no use for Numbers, really). If I was an Excel type of guy I guess I'd go with Libre or MS, but thankfully I'm not. I do a lot of presenting so I like Keynote best of them all. I have LibreOffice and use it mostly for demos of what's possible for free, but I find it fugly, buggy and incomplete. It causes my anti-cubicle rash to kick in.
PS. Since you said "productivity" rather than just "office software" let me commend Reminders (LOVE IT), Notes, Fantastical (third-party menubar add-on for Calendar), Evernote (cloud based note/scrap storage) and Dropbox/Box/SkyDrive/Sugarsync/et al.