Ask Slashdot: Most Underappreciated Sci-Fi Writer?

mvdwege writes "In the thread on the most depressing sci-fi, there were hundreds of posts but merely four mentions of John Brunner, dystopian writer par excellence. Now, given the normally U.S. libertarian bent of the Slashdot audience, it is understandable that an outright British Socialist writer like Brunner would get short shrift, but it got me thinking: what Sci-fi writers do you know that are, in your opinion, vastly underappreciated?"