Your goal is laudable and I support it 100%.
So let's figure out a way for you to do so without going too far outside the lines.
With zillions users and kerjillions of posts over almost 200 sites wide open to the internet, SE has found an amazingly successful recipe starting with great vision and being fine tuned over time.
So @OrganicMarble's logic is inescapable; we should not ask admittedly off-topic questions.
Enter Captain Kirk and "damn your logic"
With a well developed community like the one here in Space SE, we can and regularly do allow and answer somewhat-soft questions as long as the answers can be supported with some combination of math, rational thought and supporting sources.
So I'd like to propose similar questions to the examples you mention that might illustrate a way forward.
What was the most interesting orbital/transfer/trajectory conceived or executed?
Could be adjusted from "which trajectory was most interesting" to something like "Which trajectories were so innovative that they generated substantial news in popular media" or were most difficult to explain to the public.
Or you could do something like "Which spacecraft mission design change most dramatically" or the most number of times, or "Which mission had the largest number of distinctly different mission design teams?"
Or you could even consider trying "Which spacecraft trajectory was least Keplerian?" and see what happens.
What was the weirdest satellite?
If you ask it, they will come Once in a while the community will find a question so unique and interesting and its answers so valuable and/or interesting that it will just let it fly as-is. I think this will be one of them.
You can start a community wiki answer if you like, but I think it's more fun for this particular question if each answer is weirder than the other.
What's the most outlandish launch system never built?
This really could potentially squeak by as-is, but not at the same time as the previous one, you don't want to "establish a pattern" :-)
But you could also refactor "outlandish" to something more quantifiable. Or you could ask something like:
"Was there ever a launch system built or at least prototyped that had little to no chance of ever working?"
This allows for multiple answers, but each answer will have to argue based on (at least some) facts.