Others may have technical reasons for preferring one over the other, but for me the differences are primarily in clarity and esthetics. (A) is more concise and thus the logging does not clutter the main flow of code as much. I also expect logging to be a global resource, at some level, so I wouldn't be looking for logging connected to each instance. If I found it in each instance, as in (B), I'd then be on the lookout for some specific purpose that made instance logging necessary. (I'd be mildly uncertain about my understanding of the code if I never found one, and mildly annoyed if I found that there definitely was no specific purpose.)