I'm on the fence about this. On the one hand, this question in and of itself is not a bad one: if we think of the site as a useful resource for information, then answers to such a question provide the relevant information.
However, there's a slippery slope effect here (what are the best books on X? what are the best lecture notes on X?) that worries me. As it is, my personal feeling is that there are more CW questions being posted right now than I'm comfortable with, and the way the SE systems works these questions constantly get promoted to the top of the queue because they tend to generate lots of activity (even if no rep points are earned in doing so)
so while I wouldn't vote to close, I'm unlikely to upvote, and might even downvote.