(General response, not specific to R)
I choose books because:
I choose online-courses because:
I look if the author(writer/speaker) is reputed for this domain. If he is in the development team, he can explain the "why it's working this way?" and it's something awesome to learn with the vision of the topic (langage or software).
Would you use a book to learn the basics on a fast-developing tool / language? And then maybe videos for the more complex and high-level concepts.
I use real books to search, digital books to learn the basics and videos for contents complex.
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