Which ones? All of them! (Mostly.)
You're kind of asking for answers which I don't think I'm allowed to give. Judge not, lest you be judged. Sorry, I didn't write the rules.
Here's the thing. Time and time again, I've seen scouts who've done these projects be the ones "in the room" (classroom, job, theater of war, community, or church) when the next big project rolls around. And, they are the ones who say, "We got this!"
It's really not about the project. It's about the scout. Are we setting our most ambitious scouts on a trajectory where they start their first major project whi