Definitely used books, both because they’re cheaper and because I feel like they have more character. Some of my books have notes or indications in them of who their previous owners were.

I have seen a lot of highly upvoted comments on reddit which were very, very wrong.

I still use reddit for help on things. But for topics that I’m less knowledgeable about (so I can’t gauge the accuracy myself), I try to just take everything with a grain of salt.