Only Microsoft's Office for Mac 2011 14.4.8 will work on your Windows Office files in their native document format. Anything else, and particularly Apple's Pages, Numbers, and Keynote will perform translation on open, and export. This can, and will, introduce differences to your original documents, especially when sharing with others in the Windows Office 2010/2013 applications.
Here is my short list.
- Office for Mac 2011 v14.4.8
- LibreOffice (latest)
The current iterations of Apple's Pages, Numbers, and Keynote are not what I would term business/professional grade applications. Apple updates them infrequently, ignores user friendly features, omits others, and has introduced default backwards incompatibility between Yosemite and prior OS X releases of these applications. Read the reviews in the OS X App Store. Even for free with a recent Mac purchase, these products will transform your mood.
The free LibreOffice is aggressively developed and designed as an MS Office replacement suite. There are occasions where it can open documents that Office for Mac, and Apple's products ignore. Extensive PDF manuals for the individual applications. Unlike Word, you can have two-up page viewing with a button click, or edit multi-page PDF. There is a forms designer. It can open nearly any document including MS Publisher and Visio documents from the Windows space. I use it.
MS Office 2015 Preview for Yosemite is available, but as its title would suggest, it is not done yet, and some features are missing. I created a single-page Word document with a DRAFT watermark. Only LibreOffice v4.4.1 was able to open this document and preserve the watermark.