Install and use both of them for a while alongside each other then decide which one suits your needs. Unless you use a lot of different document types then personally I would say that the UI is more important.
"I've always been mad, I know I've been mad, like the most of us..." Pink Floyd
Almost nothing will completely convert from one format to another without something being lost or "different". That being said, I once sort of scoffed at Kingsoft Office and it's inability to directly convert M$ Word docs (docx). But after using it on a recently-purchased tablet and having my resume look just as it did in MS Office (2007), I'm rethinking my opinion of it. I mostly use OpenOffice/LibreOffice on PC's here at home and at work (LibreOffice is available as a portable app), but as suggested above, there's no reason (providing you have the HDD space to spare) why you couldn't use both. You could also install Kingsoft on the hard-drive and use the portable version (see link below) of LibreOffice on a USB drive if needed:
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