Personally, I've been really enjoying the technical side of vanilla minecraft. Like building farms, machines and automation. So after I saw you mention quarries, I wanted to share my recent project. This machine destroys over 5 million blocks in total, and it's so satisfying to see it run.

Man, just as that style of quarry fell out of popularity for being too laggy, Mojang went and fixed the cause of their lag. Now massive pits would be cool, but everyone uses direct replacement quarries or even just ore generators.

On the other hand, you could make a good ol' pit quarry yourself with Create! It's a bit harder, and probably more likely to break, but definitely impressive and unique.

A lot of the modern packs have quests. It could be considered finished when you complete all of those, which I haven't. Now I'm playing DW20 which doesn't have quests, so I can avoid all those judgemental looks I was giving myself.