In my opinion, it doesn't get any better than this forum if you want the widest possible access to a huge range of topics and discussions on Bitcoin. The local boards are also helpful, if they happen to support your country/language.
I've been to the other forums mentioned above, nothing's made me stay like this one has (although I actually only returned here after two years and losing my original account). Here's another link from the Bitcoin wiki:
https://en.bitcoin.it/wiki/ForumsIf you actually still like IRC, on freenode there are a few channels... not only are they generally spam free, they're very quiet when I visit =p
I might add that the Bitcoin and crypto sections on Quora are really picking up... spam seems more controlled there, and you get a really different crop of people.