If there are several different links to online content for a particular ebook or journal in WorldCat, which one should I pick?
Answer
If it's an ebook it doesn't really matter - the content of the book will be exactly the same across all platforms.
If it's a journal and you get a choice of sources, look at the database coverage. For example, one might offer access from 2000 to 2010, whereas another might offer access from 2000 to the present - which one you pick will depend on what you are looking for. Again, the content of the journal or article will be exactly the same across all sources, it's just the coverage that will vary.