You're quick to say "to me" in your comparison.

My experience is very different than yours. Codex and CC yield very differenty result both because of the harness differencess and the model differences, but niether is noticeably better than the other.

Personally, I like Codex better just because I don't have to mess with any sort of planning mode. If I imply that it shouldn't change code yet, it doesn't. CC is too impatient to get started.

I guess yes, that's a harness difference, and you can also configure CC as a harness to behave very differently, but still with same harness and guidance, "to me" there's still a difference in terms of Opus 4.6 and e.g. GPT 5.4 or which GPT model do you use? I've been using Claude Code, Codex and OpenCode as harnesses presently, but for serious long running implementation I feel like I can only really rely on CC + Opus 4.6.

Yes 5.4

Perhaps Opus is superior and I'm just jaded.

I come from Cursor before having adopted the TUI tools. Opus was nothing short of pathetic in their environment compared to the -codex models. I would only use it for investigations and planning because it was faster.

Like you've said, though, that could just be a harness issue.

I have the opposite experience. Codex gets to work much faster than Claude Code. Also I've never seen the need to use planning mode for Claude. If it thinks it needs a plan it will make one automatically.

I'll drink to the idea that it's all in my head.

It depends what you're asking it though. Sure, in a software development environment the difference between those two models is noticeable.

But think about the general user. They're using the free Gemini or ChatGPT. They're not using the latest and greatest. And they're happy using it.

And I am willing to bet that a lot of paying users would be served perfectly fine by the free models.

If a capable model is able to live on device and solve 99% of people's problems, then why would the average person ever need to pay for ChatGPT or Gemini?

But even other tasks, like research etc, where dates are important, little details and connections are important, reasoning is important, background research activities or usage of tools outside of software development, and this is where I am finding much of the LLMs most useful for my life.

Even Opus makes mistakes with dates or not understanding news and everything correctly in context with chronological orders etc, and it would be even worse with smaller and less performing models.

Scheduling, planning, researching products, shopping, trip plans, etc...