We've already discussed and criticized, extensively, the NPR "top 100" SF and fantasy books list. But take a look at this: a flow chart for choosing a book to read from the list. (It starts in the top middle.)
I link to this because I consider it immensely clever and funny. But I note that it has two problems. First, it's limited to books on the list, and as already noted it's a severely deficient list. The other problem is that it's based on the same principles that a lot of more serious "If you like A, try B" recommendations in the SF/F field, and these are principles that would not have been useful to me when I was still learning to explore the field, and that principle, essentially, is that recommendations are based on superficial features of subject matter, and not on the book's deeper approach, still less on whether it's any good.
I know this is a problem because every time I see one of these "If you like A, try B" lists, I look up books I love and find myself being recommended to try total crap that superficially imitates it. Now this flow chart is at least different in that it's trying to separate tastes rather than combine them. But if you don't already know where the lines are going, it'll be awfully hard to determine which choices will take you to classics and which to sludge.