Users who’ve seriously used both GPT-5.4 and Claude Opus 4.6: where does each actually win?

A detailed Reddit discussion among expert AI users has surfaced a nuanced, side-by-side comparison of OpenAI's GPT-5.4 and Anthropic's Claude Opus 4.6. The thread, started by a heavy user seeking stable differences beyond first impressions, reveals a consensus on specialized strengths. Claude Opus 4.6 consistently wins praise for superior reasoning under tight constraints, exceptional instruction fidelity, and reliable performance across long-context sessions with minimal drift. Users report it handles complex, technical prompts with greater depth and exhibits fewer hallucinations in reasoning-heavy tasks, making it the preferred choice for analytical work and document synthesis.

Conversely, GPT-5.4 is highlighted as the stronger tool for practical coding and debugging workflows. Its performance is noted to be more robust when dealing with unforgiving, narrow, or poorly-scoped prompts, often delivering more concise and actionable outputs. While Claude is frequently described as feeling 'smarter' or more thorough, users point out that GPT-5.4's 'token burn'—or rate of context window consumption—is often more efficient in practice, a critical factor for extended sessions. The gap is described as significant but not universal; the best model depends heavily on the specific task, with Opus leading in raw analytical power and GPT-5.4 excelling in iterative, output-oriented technical work.