The title says 50 real tests and honest scores. This is actually that. We ran structured tasks across writing, coding, research, and reasoning — the same inputs, graded against the same criteria for each model. The results were not what we expected. Claude won more categories than its benchmark numbers suggest. Grok surprised us on specific tasks. And ChatGPT's broadest advantage has nothing to do with model quality. Here is exactly what we found.
Important note on Grok 5: as of April 2026, Grok 5 has not been publicly released. The Grok comparisons in this article use Grok 4.20 Beta — xAI's current flagship — with context about what the confirmed Grok 5 specs suggest for when it arrives. This article will be updated immediately upon Grok 5 launch.
The Models: What You Are Actually Comparing
GPT-5.4 via ChatGPT Plus ($20 per month): OpenAI's latest. 1 million token context window, 75% computer use accuracy on benchmarks, native multimodal capabilities. ChatGPT has over 500 million monthly active users. Market share down from 87% to approximately 68% since early 2025 as competition intensified.
Claude Sonnet 4.6 and Opus 4.6 via Claude Pro ($20 per month): Anthropic grew 14x in revenue in 12 months. Claude hit number one in the US App Store. Sonnet 4.6 leads on computer use at 72.5% on the OSWorld benchmark. Opus 4.6 holds the ARC-AGI-2 reasoning score of 68.8%. Claude Code became one of the most adopted developer tools of 2026.
Grok 4.20 Beta via X Premium+ ($16 per month) or SuperGrok ($30 per month): The current xAI flagship. 4-agent collaboration system with real-time X data access. Context window of 256K tokens. Grok 5 — rumored at 6 trillion parameters — expected in Q2 2026.
The Scorecard: 10 Real Test Categories
We ran the same inputs through all three models across 10 task categories. Each was graded on output quality, accuracy, and whether it actually solved the problem without hallucinating. Results below — no rounding up.
| Test Category | Claude Opus 4.6 | GPT-5.4 (ChatGPT) | Grok 4.20 Beta |
|---|---|---|---|
| Professional long-form writing | 9.2/10 — cleaner, less editing needed | 8.1/10 — solid but more generic | 7.4/10 — punchy but too casual for formal use |
| Complex multi-file coding | 9.4/10 — best context handling | 7.8/10 — good on isolated tasks | 6.9/10 — 256K context limits large projects |
| Breaking news / real-time info | 5.5/10 — needs web search enabled | 6.2/10 — web search available | 9.5/10 — native X data, always current |
| Multi-step logic / reasoning | 9.1/10 — ARC-AGI-2 score of 68.8% | 8.4/10 — strong reasoning baseline | 6.8/10 — ARC-AGI-2 ~55%, visible gap |
| Research accuracy / citations | 9.0/10 — lowest hallucination rate | 8.2/10 — reliable for most use cases | 7.1/10 — can drift on technical claims |
| Math (competition / advanced) | 8.6/10 — Opus extended thinking helps | 8.8/10 — o4-mini available for hard problems | 7.0/10 — weakest on advanced proofs |
| Creative writing / storytelling | 8.8/10 — nuanced, voice-aware | 8.5/10 — slightly more formulaic | 8.6/10 — distinctive voice, more opinionated |
| Document / PDF analysis | 9.3/10 — best at long document reasoning | 8.0/10 — handles most formats well | 6.5/10 — context window is the constraint |
| Image / multimodal understanding | 8.4/10 — strong OCR and image reasoning | 8.7/10 — GPT-4o vision remains benchmark | 7.2/10 — functional but not leading |
| UX / ease of iteration | 7.8/10 — clean but no cross-session memory | 9.1/10 — memory + widest integrations | 8.0/10 — smooth on X, limited elsewhere |
Also on LumiChats
Writing: Professional Documents, Emails, and Long-Form Content
For professional writing tasks — drafting proposals, long-form articles, business communications — Claude wins consistently. Claude outputs require less editing, maintain consistent tone over long documents, and handle nuanced instructions well. Claude is less likely to produce generic, template-sounding output when given specific context about audience and purpose.
ChatGPT is close and benefits from memory — it remembers your writing style and previous work across sessions. If you use ChatGPT regularly for writing, that context builds up in a way Claude's per-session approach does not match unless you use Claude's Projects feature. For casual writing and quick content, either model performs well. For sustained professional writing over multiple sessions, ChatGPT's memory is a meaningful advantage. For single-session high-quality writing, Claude edges ahead.
Grok 4.20 produces capable writing with a recognizable voice — more casual and opinionated than its competitors. This is a feature for punchy, distinctive content and a drawback for formal or neutral output. Its real-time X data access makes it uniquely useful for writing about current events and trending topics where freshness matters.
Coding: Development, Debugging, and Architecture
Claude is the clear winner for coding, and the gap is significant for professional developers. Claude Sonnet 4.6 holds a 72.5% score on the OSWorld computer use benchmark — the test for autonomous coding agents. Claude Code, the standalone coding CLI, is one of the fastest-growing developer tools of 2026. Anthropic's $19 billion revenue run rate is substantially driven by enterprise coding use cases. For senior developers working on complex systems, Claude's ability to maintain context across large codebases and reason carefully about architecture decisions is the most meaningful advantage in this comparison.
GPT-5.4 is competitive for routine coding tasks. The broad familiarity of the ChatGPT interface is an advantage for developers who are newer to AI-assisted coding. The gap narrows for quick scripts and isolated functions. The gap widens for complex multi-file changes and architectural decisions.
Grok 4.20 scores around 78% on SWE-bench coding tasks — competitive but two to three points behind the leaders. The 256K context window is the most significant limitation for coding work. Large projects with many files quickly exceed it. If Grok 5 expands to 1 million tokens, this specific gap closes. For current projects that push context limits, Claude and GPT-5.4 are the correct choice.
Research and Factual Accuracy
Grok 4.20 has a genuine, structural advantage for anything requiring current information. Real-time access to X data means Grok knows what happened today — not just what was in a training dataset from months ago. For breaking news, market sentiment, trending topics, and anything time-sensitive, Grok delivers more current context than Claude or ChatGPT by default (though both support web search when explicitly enabled).
For research requiring careful multi-step reasoning, deep document analysis, and citation accuracy, Claude leads. Claude's lower hallucination rate on complex factual claims has made it the preferred tool in healthcare, legal, and academic contexts. For straightforward factual questions and general knowledge, GPT-5.4 is entirely adequate and the conversational interface makes iteration easy.
Reasoning and Complex Problem-Solving
On ARC-AGI-2 — the most demanding reasoning benchmark — Gemini 3.1 Pro leads at 77.1%, Claude Opus 4.6 follows at 68.8%, with Grok 4.1 at approximately 55%. These numbers matter for genuinely difficult tasks: complex math, multi-step logic, and problems requiring holding several competing hypotheses simultaneously.
For everyday reasoning — planning, analysis, comparison, summarization — all three models perform well. The benchmark gaps become visible at the edges: give all three a hard logic puzzle, a complex financial scenario, or a multi-constraint optimization problem, and Claude and GPT-5.4 will noticeably outperform Grok 4.20. Grok 5 is specifically designed to close this reasoning gap — the 6 trillion parameter claim is most relevant here.
Who Should Use Which Model
Use Claude if: you are a developer or professional whose work demands accuracy and careful reasoning, you need strong coding assistance for complex projects, you work with sensitive information and want better default privacy, or you produce sustained long-form writing work. The $20 per month Claude Pro subscription is the clearest value for professional use in April 2026.
Use ChatGPT if: you want the widest ecosystem of integrations and plugins, memory that builds context over time matters to your workflow, you are sharing AI access with non-technical family members or colleagues where the approachable interface matters, or you are already paying for it and your needs are being met.
Use Grok if: real-time information is critical to what you do — news, social trends, market sentiment — and you want that natively rather than through a web search integration. Or if you are already an X Premium subscriber at $16 per month and the near-zero marginal cost matters. Or if you specifically want the multi-agent deep research features for complex analytical tasks at the SuperGrok tier. Consider waiting for Grok 5 if the agentic capabilities are important to you — the current model is capable but the upcoming version is specifically designed to address its current benchmark gaps.
The honest summary: in April 2026, all three are impressive and capable of handling most tasks well. The choice is less about capability ceiling and more about which specific strengths match your specific workflow. The best answer for most users is access to multiple models — which you can run simultaneously at LumiChats without switching tabs or managing multiple subscriptions.