I like the new format. The reason it still feels like "home" for me is very simple: there are quite a few members here that I like, regardless if we agree on movies or not, and I always enjoy reading their posts.
I don't know the statistics but if the forum isn't as active as it used to be, as many have already mentioned, it may just be because the format has matured, it's been accepted, it is (I think) relatively successful commerically. We're not in an "early adoption" phase anymore, we know what to expect. Once it's been stated that there's too much this and not enough that on a particular release, there's not much left to say. I buy Blu-rays because I love movies, and I love watching them in the comfort of my modest setup.
When Blu-ray was a new format, a lot of the troubleshooting had to do with discs being not compatible with all players, glitches everywhere for everyone. Now things are different, nobody has playback issues anymore (or in rare occasions), so we're left with "faulty" transfers from the "lazy" studios that don't respect their customers etc...
A forum is usually to report problems. Today Blu-ray doesn't have that much of them. The movie discussion forum is quite active, and frankly, I prefer discussing movies than trying to figure out a proper level of white in Photoshop. Doing custom covers for my Blu-ray collection is a better hobby
There are numerous other places indeed, but I like AVS, and I like its community. So I'm stuck here