Interpreting your question as 'thinker who is/was an atheist': of that list, definitely Daniel Dennett. Better than him, though: David Kellogg Lewis (I wonder if his ideas might be a good substitute for the religious - you get an even more insane ontology than is provided by the average religion, but this time it's supported by well-considered, mostly consistent, and beautifully eloquent, rational arguments). Neither for what they've said about atheism, but they are / were respectively (sadly) both atheists.
Interpreting your question as something like, say, 'thinker who has made the best contribution to atheism': not sure. Nietzsche was pretty cool, but I'd probably go with Dennett again. I haven't read much that's directly in defense of atheism, largely because I take it as the obviously best position, and I also haven't gotten round to reading much about the psychology and evolution of religion, although that's a topic I'm very interested in.
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"There is no idea, however ancient and absurd, that is not capable of improving our knowledge."