Hardcover, softcover, digital? What is your preference?
The question has the order right: I prefer hardcovers, mostly for durability, then softcovers, and then finally digital. I have a few digital RPG's but I find them difficult to read. I'm old enough that my brain reads books, by that I mean that it skips around looking for highlighted and critical parts before settling on the actual text. That's harder to do when you're only seeing a fraction of a single page.
Plus I like the tangibility of a book that I can read in bed or in the bath or where ever.
I will say this: the rise of digital warehouses of RPG material like drivethrurpg or lulu has allowed a lot of games to see the light of day that wouldn't have twenty years ago. I've partaken of drivethru's Print on Demand options on more than one occasion and often it is a very affordable way to get the tangible copy of an RPG.