I used to read more fiction than non-fiction, but that has reversed as I've gotten older. This evolution happened slowly and without me being consciously aware of it most of the time, but recently I've been wondering "why?" What I've decided is that there is more good but non-challenging non-fiction than there is fiction.
Some books are challenging to read -- and that's great. I like a good mental workout. But it can take me a month or so to work through a book like that. For instance, right now I'm reading Anti-Judaism: The Western Tradition by David Nirenberg. It's excellent and I highly recommend it, but it's also exhausting! I can read maybe 20 pages of it a night, four or five nights a week.
So often I want something a little lighter. I might read 2-4 challenging books in a year, but something like 8-10 easier ones. The problem is that while I want something "lighter" and "easier," I still want those books to be intelligent, well-written, etc. In short, I want them to be good. Sometimes this is a problem.
Both fiction and non-fiction can be challenging or non-challenging, as well as good or bad. What I've found is that it's much easier to find non-challenging but still good non-fiction. With fiction, books that are non-challenging are often pretty bad, and books that are good are often fairly challenging. For example, a while back I read the Song of Ice and Fire books. The first few were great! Dead center in the venn diagram overlap between non-challenging and good. But as the series progressed, the books started to get more ... well, bad. The most recently one, while still not challenging, was also not very good.
If anyone can recommend novels that are both good and non-challenging, I'd love some suggestions!