Opus 4.6 or Codex – Which One Are You Actually Using?

Hey guys,
I’ve been testing both lately and honestly can’t decide which one is better for realworld use.
Claude Opus 4.6 feels stronger when it comes to deep reasoning and handling large projects. When I throw a big codebase or complex system at it, it seems to “think” more architecturally.
On the other hand, Codex feels faster and more practical. For writing scripts, quick fixes, automation tasks, and terminal-style work, it seems smoother and more efficient.
For those of you actually using them in production:

Which one makes fewer mistakes on larger projects?
For affiliate / automation / bot setups, which is more reliable?
Which one makes more sense cost-wise (token usage vs output quality)?
Not looking for benchmark stats I’m more interested in real user experience.

Would appreciate honest feedback.

Opus 4.6 is much better. I use Opus 4.6 effort:max in Cursor for frontend and Opus 4.6 effort:high in Claude Code cli for backend.

I'm not sure what is the most cost efficient but probbaly Codex is more cost efficient.

In my experience Cursor with Opus is the fastest. CC with Opus fast enough. I had problems with looping with Codex.

> For affiliate / automation / bot setups, which is more reliable?

need to be more specific what you're doing exactly

For big projects, Opus 4.6 usually makes fewer structural mistakes and handles complex logic better.

For affiliate setups, bots, and quick automation, Codex feels faster and more practical day to day.

Cost-wise, Codex often gives better value for routine tasks, while Opus is worth it when you need deeper thinking.

hizircancakiroglu said:

Hey guys,
I’ve been testing both lately and honestly can’t decide which one is better for realworld use.
Claude Opus 4.6 feels stronger when it comes to deep reasoning and handling large projects. When I throw a big codebase or complex system at it, it seems to “think” more architecturally.
On the other hand, Codex feels faster and more practical. For writing scripts, quick fixes, automation tasks, and terminal-style work, it seems smoother and more efficient.
For those of you actually using them in production:

Which one makes fewer mistakes on larger projects?
For affiliate / automation / bot setups, which is more reliable?
Which one makes more sense cost-wise (token usage vs output quality)?
Not looking for benchmark stats I’m more interested in real user experience.

Would appreciate honest feedback.

Click to expand...

I do not know, they all have some cons and pros way beyond to what you have listed.

For example, can you deploy to your domain while preserving the chat interface?

Can they escape the sandbox and write to the database, if they can only be granted select() permission, that is a bit troublesome.

How good do they respect system prompts and guardrails, sometimes they forget.To me, cross file and cross context reliability(aka FE, BE, DB) and memory is the most important, and it should never just overwrite or invent new variable names.

Some of them consistently try to put logic decision and even storage on the front end, which is very tiresome and often catastrophic, I had claude trying to do session management via front end while it fully knew there is an express back end.

I believe they all need ...you getting used to them, case by case.

I use these via embedding and system prompts with fallbacks in case one is down but they all interpret the prompts slightly or totally different.

Thanks for all information .