Libre Office, which shares a lot of similarities with Open Office, can save files in the newer docx and xlsx formats.
As a rule, OO is updated less frequently and with fewer new features than LO; OO is therefore sometimes dated, but is also less prone to bugs.
I pretty much only use LO these days, though I used to use OO a lot. My preference is for LO, mainly because it's able to save documents in the latest MS Office formats, that are frequently requested by organisations and individuals who exclusively use MS Office.