Advise on story for "tell me about a time you had a conflict"

You shared the "table of contents" version, so it's hard to know without the details.

Here's some advice:

• What, specifically, was hard about this situation? If there was no challenge, then it's not an interesting story.
• Once you identify the challenge, you can build your story-telling around this challenge.
• Collect "supporting evidence" for the challenge. Was your coworker more senior than you? Were you emotionally invested in your approach? Were they? How long did it take you to get to a conclusion? What specific steps did you take to make an informed decision? What was the Impact?
• Finish off with your learning. You mention that their approach made more sense. In what way? Why didn't it make sense to you initially? How are you a stronger engineer today as a result of this experience?

Your worry that the story is too simple and ends too cleanly isn't an issue if there was a real challenge.

The absolute worst thing that you can do is choose someone else's story. As an interviewer, I care much more about your answers to the follow-up questions than to the "tell me about a time..." question.

Good luck!