I find both Opus 4.6 and GPT-5.4 have weaknesses but tend to support each other. Someone described it to me jokingly as "Claude has ADHD and Codex is autistic." Claude is great at doing something until it gets done and will run for hours on a task without feedback, Codex is often the opposite: it will ask for feedback often and sometimes just stop in the middle of a task saying it's done with step 1 of 5. On the other hand, Codex is a diligent reviewer and will find even subtle bugs that Claude created in its big long-running "until its done" work mode.