If this were a poll,

[ShadowHM]

I think I likely am at the top end of range 6 right now. I have done two massive book purges in my past (besides regular whittling as time goes by). Both were occasioned by moves, the more recent one being about two years ago. I had to have one entire wall in my living room converted to shelves to accommodate the collection, and still have three more bookcases in that room plus one bookcase per bedroom. Plus the books at the cottage...

Most of the books I have kept are non-fiction. I have rather a lot of history books and texts, old textbooks (fifty or more years old, for perspective on what and how history topics were taught), a large selection of Do It Yourself manuals, another large selection of 'outdoor information' guides (many of the Field Guide to... series and similar ones), wine selection guides, photograph books (of the sort that used to be called 'coffee table' books), quite a few dictionaries and related books and a number of atlases of various types as well as a growing collection of books on the subject of evolution and human attributes. I do still have a small collection of CanLit, Speculative Fiction and Children's fiction.

As Pete said, I would be unlikely to bring fiction to that desert island. But I would be hard pressed to select only three topics to last me a year.

Much as I like music, I would not trade any books for music.