Why I don't read many atheism blogs
Most atheism blogs in this sense seem dedicated to endlessly re-hashing what are basically the same debates and arguments we've been having with god-believers for decades, if not generations. I had my fill of those arguments quite some time ago -- long before the internet was on the scene, in fact -- and I find little interest in repeating the same conversations over and over.
More fundamentally, I've come to concur with Pat Condell that the best way to confront religion is via ridicule, not debate -- because religion is inherently ridiculous, and the most effective way to combat it is to highlight this. Trying to have a serious "debate" about the befuddled hash of incoherence that passes for "ideas" in religion means according religion a seriousness and credibility and respect that it simply does not merit. It's like "debating" the "stork hypothesis" of where babies come from; the mere act of attempting such a debate would dignify the absurd.
A blog whose approach to religion I do like (though religion isn't its sole topic) is Pharyngula.