My experience using AI for coding: Opus is like a humanities student—highly intelligent; you say one thing, and it performs three steps accordingly. Codex is like a science student—meticulous; you tell it one thing, and it does exactly that, never doing anything extra or building anything unexpected. If you have little coding experience, you'll find Opus much better. If you're already proficient, you might use Codex more often. After all, it's cheaper and more efficient.