The best aviation forum user experience I have seen or used is the SuperCub.org forum. I wonder what they use for forum software? To be honest, the worst forum user experience I had was with the previous rotarywing forum, so this change is great. It was very hard to find new posts, took very long to open one, and often would fail if tried to post. Complete opposite now. The home page on the Supercub.org forum lists all the new posts which I like a lot. They also have member only boards which is nice to post privately to members only without being open to the whole Internet to read. There are different membership levels to join too.