Non-fiction for me. I can't learn enough about this world. Fantasy and a good mystery challenge my mind, too, but only those with little fluff.
I do pretty much the same thing - I also love learning things. But lately, I find myself thinking about all the delicious fiction books of different genres that I also want to read. Like you, I don't simply want fluff - it must be something that I can learn from and it must leave me with something to think about. That's why I just LOVE the Harry Potter series.
Me, too! That work is packed with symbolism; each time I go back and re-read them, I layer out more. Brilliant work. A true classic.
Fiction, like Potter, is non-fiction, to me. It delivered a non-fiction message using fantasy, and that is the only way to get some controversial topics out. Sagan did that with his novel, Contact. I believe the message he sent was an autobiographical (excluding the gender) message of something Sagan knew to be real. Fiction was the only way he could get mainstream to pick it up, though. And Jodi Foster had a very difficult time pitching the screenplay. She wound up financing a big portion of it due to lack of interest - lack of vision and lack of general understanding. JK got her points across in a big way using fantasy and fiction. Brilliant.
I definitely read more fiction than non-fiction (n-f), but I do enjoy both.
As a writer, reading is a journey for the the imagination. It takes me places that I might not have found on my own. It feeds my writer-soul. Story begets story, and I rarely make it through a novel without a few ideas forming and evolving while I read. No, not plagaristic. Its an organic brewing, the mind siezing upon an idea, then musing and building upon it in unique ways.
Fiction reveals truths that reality obscures.
~~ Ralph Waldo Emerson ~~
Yet, as a writer, I also read a lot of non-fiction. Research is a huge part of writing good fiction. Facts, well placed, expand a story and help to better immerse the reader. Too many facts bog a story down. It's a fine balance. And, with good n-f there is also a balance. I've read some n-f books which are real page-turners because the author writes so engagingly. I've read others that are almost painful to read because of their dry, convoluted, or overly-technical writing. (These work wonders when insomnia hits or doorstops are needed.)
If the reader is open to it, there is something to learn in both fiction and non-fiction. Learning need not be the only reason to read, though. Some books have great entertainment value, others expand our consciousness or question the status quo. These are all relevant. Best of all, no matter which form we read, our brains are healthier for it!