@igm,
If an atheist said "it’s not logical to believe in God" it would be because no logical reason has been forthcoming. It's the lack of convincing evidence that stops the atheist from believing god exists. On the other hand, an agnostic neither believes nor disbelieves in a god. Agnostics assert that it's impossible for human beings to know anything about god.
As for which position, atheism or agnosticism, is more logical, I can only ask which is most reasonable:
1) To outright deny the possibility of ever knowing whether god exists, or
2) To accept the possibility that god exists, but lacking evidence, to withhold belief.
Looking at the agnostic position one has to ask; where does such knowledge about the impossibility of knowing anything about god come from? Just how do they know it's impossible? Personally, I don't think they know any such thing at all. Therefore, atheist "are more logical."