Hmm... I've thought about this myself, as I have memberships at all three sites. I often look to mefi for informative content and skip the threads entirely, and mofi does seem a bit redundant. It's been nearly a year since I've posted anything there. Mecha supplies more of a real community though, and this is reinforced by the sheer volume of meetup activity.

Now that I think of it, I think the high ratio of face to face interaction brings a level of respect and politeness you don't see at metafilter.

Now the circle is complete.

I also have memberships at all three sites, but MonkeyFilter just never clicked with me for some reason. Perhaps because of the whole "monkey" thing which I never got (the "bunny" thing I don't really get either, but they're more innocuous or something - plus I figure it's just me).

I think one of the main reasons I stay away from MoFi nowadays is the sense of inferiority that pervades. Because it was (kind of) conceived as a waiting-room for MeFi, it always seems to have a "second-best" air about it. Maybe that's just me too, though. Because MeCha was born as an alternative venue to MeFi rather than a substitute for the membership-challenged, this place developed a more positive persona.

Or, I'm just talking out my arse again.

I'm an "all three sites member" too. I can no longer access any of them at work, except via Google Reader and when I'm here at home, MeCha gets most of my attention (for the community feeling mentioned above). MoFi, I'm afraid, gets the least.

The main reason I stay away from MoFi is because I find it visually unappealing* and difficult to read.

* Read: MoFi doesn't have a bunnyhead zombie boy.