At a departmental function this weekend I had a nice chat with a scholar I trust. I asked him which monograph series he encourages his own doctoral students to publish in. He had recommended specifically Walter de Gruyter and Mohr Siebeck. I had asked him why he did not mention the UK publishers. He commented that a well-known UK series has a policy that they want short 80,000 word manscripts, following the trend of some universities which have set their max word limit at 80K for theses. Since Durham is still at a 100,000 max limit, it would be difficult (though not impossible) to cut it down to their liking for publication. This is something significant that I had never thought about before.I had mentioned that it seemed like Mohr Siebeck did not seem like a really exclusive series since they seemed to put out so many volumes per year. He mentioned that they have revamped a bit and now are much stricter.
Though there are many factors to consider, these are a couple worth noting. Also, I heard that if you are interested in doing a post-doc in Germany, it helps to publish your thesis in a German series – this may just be a rumor, but it does make some sense.