I suppose it depends on what you’re looking for. Fluther and AB are really different.
In fact, it’s not to be mean or criticizing or nothing, but I don’t actually understand why the AB people all moved to Fluther, both places are quite different. (I did too obviously, not bashing anything.)
AB is bigger, and so it’s faster and more active, but you will always get your share of bullshit and drama, such as Conservatives VS Liberals and Atheists VS Christians. There are a lot of smart people there, but also has its fair share of ass. Still, it’s better for time wasting.
Fluther is a little more serious, and even being a smartass or writing something witty is a project. Which isn’t bad, I mean it’s nice to know I can learn something, but it doesn’t encompass the general reason why people come online after work, for example. i mean sometimes I don’t feel like being serious, and this really isn’t the place to tell everyone that I’m actually Batman.
Blurtit is similar to AB, but it’s more about technical stuff. You can’t really debate evolution or piss of fence sides. It’s also pretty ghost town as far as I see.
So Fluther is good for some, and not others. You have to take all the factors which define each, for the majority, and see what you enjoy.
The interaction is much different too, Fluther seemingly aiming more for a hands on approach rather than the AB scheme, if only because, well looking at it personally anyways, this place works more like a traditional forum.