My biggest gripe with Freenode is that a lot of popular channels are silent. Hundreds of users, but all lurking with very little conversation going on.

For me, the best channel was always #csharp. Every time I logged in, there was always a group of people talking. Any time I had a question, I could ask it and a handful of people would either give you the answer or would talk you through the problem and help you come up with an answer. That kind of guidance is often lacking from modern programming forums/q&a sites.