I, personally, can not point you in the direction of a Development Forum that is informative and good quality simply because I haven't explored this site fully. That, I am sorry for.
I can, however, point out that the genre of my Hub is Personal Development. It's not perfect, but it's a work in the making :)
As for which forum to participate in?
What's helpful for me (and how I, myself, do this) is that I will give my "2 cents" in a forum or indulge in a Hub if it relates to me and/or I am able to give a helpful response to it. If i'm unable to give advice or whatnot, then I make sure to keep my words to myself.
Remember, these are only my personal rules. Everyone is different. Just do what feels comfortable to you. You'll know when it happens :)
Hope this post helped you out!