I enjoy all three of the big group blogs, especially since they are all quite different, and generally are discussing completely different topics. However, I happen to comment more often on T&S. Steve Evans asked a few weeks ago why I don't feel comfortable commenting on BCC. I said something about not quite feeling like part of the group there, but I think that's not quite it.
I've been hanging around the LDS blogs for a year now, and I feel like I generally know most of the regular posters and commenters (you don't know who I am, but I know who you are, which also adds to the reluctance in commenting). I have found the posters at BCC as a whole to be very friendly and respectful, along with the posters at T&S and M*.
The reason I don't comment over there much is that I really don't have anything to add to the discussions. I love to read the posts and comments, but I don't think I have a part in the discussions, since I don't relate to many of the concerns raised. I love to read about different viewpoints. I agree with many points raised at BCC. But overall, it's not quite me.
I do write out a lot of comments though. I have discovered that typing out a comment, but not posting it, is rather satisfying.
I still wish there were more commenting as a whole around the LDS blogs. BCC is good, as Steve pointed out, but it's always a bit galling to see long discussions with very little input from women. I'm still looking for that good LDS women's group blog. I expect it is just wishful thinking. [Danithew pointed out the FMH is an LDS women's group blog, and I completely agree. I should have clarified by saying that I'd like to see one that discussed more things than specifically "women's issues."]