I joined some forums but Bitcointalk is the best. I like it interface and simplicity than other forums, that is first impression and I never like other forums because of their interfaces and too many ranks, icons that looks very messy. Next is more important, quality posters are in Bitcointalk and other forums can not compete with it.

If you mention about altcoinstalks.com forum, why don't mention about Bitcoingarden forum?
I don't like it too but I summon it here because the admin and owner of Bitcoingarden has an account on Bitcointalk and he is still actively. Maybe waiting for chances to get some prominent members from Bitcointalk to Bitcoingarden. 

This user S3cco