Personally I choose to avoid films of books I adored because I tend to be disappointed by their adaptations. If I do see and read, I prefer the film first because I know there will be lots more detail in the book and sometimes a completely different ending! This does mean I don't get to imagine characters and locations though because I envisage what I have seen - even when, with films such as Still Alice for example, the main character's appearance bears no relation to the written description. I also tend to use BBC television adaptations as an excuse not to get stuck into some classics, especially the ones with small print and hundreds of pages!
These are the literary adaptations I'm selling on eBay right now: (Click on each photo to visit its sale page!)