My latest position was SDE II at Amazon, backend. I was laid off. I have not worked for 2 years. I find myself struggling with which project I should talk about in my interviews. Here are the projects I had worked on.
“Most challenging” doesn’t always mean the most successful or impactful but it would be nice if you had an example that happened to check both boxes.
From there, I would try to orient these on both of those axes (maybe a few more):
It will not be straight forward to “score” for these dimensions, and when you get a result it may still be ambiguous, but hopefully this exercise can still help you index.
Argh, this one is tricky - All of them have caveats.
#5 was the clear winner as I initially read it, but that the fact that it never launched is awkward. You can spin that as a semi-positive by sharing the learnings you got from it and ideas you now have to derisk projects in the future.
After that, #3 maybe? #4 seems decent but if you don't remember enough to deliver a solid narrative about it, that's a no-go.
Since you are SDE 2, I am personally looking for strong independence and ownership. That's why #5 stood out to me; the other projects didn't have as much of that.
Start with the ideal feeling you want for the person interviewing you. I'd argue that you want them to think not only "This person has handled technically sophisticated products" but also "This person was resourceful with their people and learning to handle large scope."
From that perspective, I like #4 and #3. IMO it's important that you had some form of launch or completion in the project as well.
For me, #3 stood out the most for the following reasons:
Technical complexity can be low, but the business impact can be high. When the prompt says "challenging", they didn't necessarily specify technically challenging.