This isn't a perfect survey, but I am a Codex user and most of my employees are pretty stuck in their workflows and were not really interested in trying even when I was saying good things (even pre-Opus 4.8).

When we work trial people, 100% of people ask for Claude rather than Codex or anything else.

When I talk to people at non-AI tech events everyone basically says they use Claude and have not tried an alternative.

Developers writ large are actually not that interested in trying multiple tools, they like customizing their chosen tool and tweaking it forever.

I think developers are as susceptible to brand marketing as everyone else. It's why almost everyone has a Macbook.