Wallpost! (lol)

The most active section of the forums are most likely contests and events (almost entirely cheap skin contests with little effort behind them), as they require multiple people to keep posting on the thread to join and submit entries. The next-biggest area of the forums goes back and forth between small server advertisement and staff applications and introductions every couple days. 4th place is, of course, shitposts and random polls.

Seems to me like it's the servers section that most reliably peaks in activity. For the rest of the site itself, I'd say skins are easily rivals for the top.

From what I've been seeing recently I'd say the most active section of the forums is probably the Introductions section. Personally I don't use these forums very much because it seems very juvenile compared to the other forums I use. When I search the forum index I see strings of polls, what skin should I make, what do you think of this MC version or that MC version, writing contests, role plays- and a large portion seems to have nothing to do with minecraft at all. In the rare instances I see "Help me Please" the content either ends up being "how do I make server?" or "how to make datapacks?" and, in the very rare instance, when the person could use some specific help it seems to have fallen from the feed and been abandoned by the author. When I joined this server 5 years ago I did so to ask a question about an issue I was having with commands in SMP- that question was never answered or replied to. Since the forum was no help I left and didn't use it again for years. Since returning it doesn't appear much has changed.

I find PMC to be a great location for cataloging and acquiring minecraft content but I've found almost any other forum to be better for questions, answers, suggestions and discussion.

While I can't give you a definitive answer and say "This section is the most active" - A lot of the people whom are online aren't peeking in the forums, they're most likely roaming around the Skins, Mods, or Projects sections as those three seem to be the most popular.

And yes the community has changed a lot over the years ( I've been here for 6 years :D ) and it really has become less active, but at the same time, it's become a lot easier to stand out amongst the crowd simply by being nice and trying to help :)