I'll start myself: I've been quite interested in Esperanto recently, and I am thinking of starting to actually learn the language. Esperanto is just really interesting to me, because of its history and size, compared to other conlangs. I don't believe it will become the universal world language, like once was dreamed. And I do think esperanto has quite a few shortcomings when it comes to being an international auxilliary language. The reason I want to learn it is more just for that history and culture.
It's been ages since I actually worked on any, but way back I got reasonably deep into Lojban
Oooh Lojban is super interesting! Really fun to think about places where it would make sense to use it. I imagine a political manifesto, or law-book would be a really good place.