Long, good weekend.
What do we have here?
I don't know.
Seriously, I do not know. I'm not sure I've ever really considered which games have great writing as opposed to being great games. Yes, I have read games with great writing, and others with poor writing, but I never made a list of the best and worst in my mind. I also don't know that I especially separated the 'writing' from the games that they're in.
Some of these questions are difficult to answer, not because the question challenges my sensibilities, or makes me think, but because they ask questions I don't really think about the answers to.
My favorite games are games I've read, and re-read many times. I suppose that had great writing. If not, I guess I love crappy writing.