I assume you want the underlying question answered, but instead you're gonna get an answer about asking such a question (that's what Meta is for). One problem is that you don't give any clue what you mean by "good". Everybody has a personal opinion about books that they like or hate: SE is not a forum for conducting opinion polls. All books are good in some respects and bad in others. If we know for example that you only want minimal coverage of theory and are more interested in NLP, that will significantly shape (focus) the answer.
Second: there are relatively few single sources on "linguistics" (weighed against the mass of specific-topic books). There are no "intermediate level" books on linguistics. At the intermediate level, you go into specific sub-areas of linguistics. I assume what you really want to know is, once you've done the intro semester course in "linguistics and language", what would be the next readings that would be appropriate, for example "what should I read in phonology?", "what should I read in syntax?", "what should I read in historical linguistics?"...Third: what is linguistics? There are dozens of sub-areas of linguistics: are you asking about all of them equally?
A complete answer would itself be a book, and it would be full of personal opinions. The question should be narrowed. Pick an area of linguistics, ask about books on the topic which are good in a particular way. If you are interested in language analysis, that's an essential criterion. If you want to understand contemporary syntactic theory, that's a different criterion. If you have in mind a career in NLP, you have a third criterion.