ChatGPT vs Claude vs Grok: Which to Use for What

ChatGPT, Claude and Grok all got meaningfully better in the last few months, and none of them is the right answer for every job. Claude is the safer pick for writing and careful reasoning, GPT-6 Astra is built for agent-style work across files and tools, and Grok is the one that knows what happened on X an hour ago. Below is what each maker actually claims, what an outside reviewer found, and which one to open for a given task.

What actually changed recently

Anthropic released Claude Opus 5.5 on September 22, 2026, the first model in a new 5.5 family, according to Anthropic's own Opus page. Anthropic says it performs at the level of Claude Fable 5.1 on most work and costs 40% less to run than Opus 5, and a separate report notes Anthropic released Claude Opus 5.5 on September 22, cutting API pricing 20%. A week later Anthropic followed with Claude Sonnet 5.5, detailed on Anthropic's Sonnet 5.5 announcement; Anthropic says it runs 30+ percent faster than its predecessor and costs up to 30 percent less for most work, pitched as a faster, lower-cost complement to Claude Opus 5.5.

OpenAI moved first, in September 2026, with GPT-6 Astra. OpenAI announced it would begin rolling out GPT-6 Astra, which the company said is the product of "years of research and big bets", starting with a cybersecurity program before reaching regular users. OpenAI's own announcement, posted to its developer community, is bullish: it calls Astra "the most intelligent and aligned model in the world" and says it achieves state-of-the-art results on Agents' Last Exam, AutomationBench, and ScreenSpot Pro, benchmarks for computer workflow tasks — worth flagging as OpenAI's own benchmark claim, not an independent one.

xAI's Grok 4.7 landed around the same time. xAI's own framing is modest: Decrypt's review of the launch reports the company called it "a notable improvement over Grok 4.6 at the same price and speed". The same outside review is more skeptical of the hype, noting that on the benchmarks, it's still in second place — a useful counterweight to the launch-day noise.

Writing

For drafting, editing and tone work, Claude Sonnet 5.5 is the practical default: it's priced at 1 credit a message in Plurel, and Anthropic's own data on speed and cost backs up why it's positioned as the everyday writing model rather than Opus. If you want a second opinion on tone or want to check how a chatbot handles longer-form content in a non-English market, one independent comparison found ChatGPT is good but sometimes sounds translated in Chinese-language writing specifically — a narrow but real data point if that's your use case.

If the piece needs the hardest editorial judgment — a legal-adjacent document, a nuanced brand voice, a long report that has to hold together — step up to Claude Opus 5.5 (1.5 credits). One broader comparison piece summarized the general reputation this way: Claude prioritizes accuracy over speed, while the same piece noted ChatGPT generates faster responses that work well for brainstorming and quick problem-solving. That lines up with how to split the work: brainstorm fast with a cheap model, finish with Opus.

Coding

Claude Opus 5.5 is the one to reach for on the hardest reasoning and coding tasks; it's Anthropic's top model, and the price cut that came with its launch makes it cheaper to iterate with than before. For agent-style coding that has to touch files, run tools, and act across a computer environment rather than just answer in a chat box, GPT-6 Astra is built for exactly that: OpenAI's own announcement leans on benchmarks for computer workflow tasks across professional settings as its headline strength, and it's available in ChatGPT and OpenAI's Codex product per the company's community post. In Plurel it costs 2 credits a message. Grok 4.7 is a reasonable third option if the task needs current, web-sourced facts mixed into the code (API docs that changed last week, a library version released yesterday).

Research with web search

This is where Grok and GPT-6 Astra earn their keep over a model with no browsing. xAI's model is built around live data from X, and the technical specifics back a claim of genuine scale: Grok 4.7 is available on the xAI API, with rate limits listed as 150 requests per second and 50 million tokens per minute. One general comparison summarized the practical feel of that as Grok delivers shorter, punchier answers packed with real-time context, which is a fair description for fast-moving news or market questions. For deeper research — a report that needs several sources checked, compared and written up with citations — GPT-6 Astra or Claude Opus 5.5 both run with a web search tool in Plurel and will hold a longer thread of reasoning better than a quick-answer model.

For a closer look at how to read citations a chat model gives you (and when to trust them), see the guide on AI chat web search and the one on Grok's web and X search.

Long documents

For anything that has to stay coherent over many pages — a contract review, a long codebase explanation, a book-length manuscript — context window and patience matter more than raw cleverness. Claude Opus 5.5 and GPT-6 Astra both hold up well here; Astra in particular is positioned by OpenAI as capable of extended, multi-step work rather than one-shot answers, which is the same quality you want in a long-document pass. If what you actually need is the output as a real file — a PDF, a spreadsheet, a Word doc — rather than just chat text, that's a separate step covered below.

Speed and price, side by side

None of these credit prices are the maker's own API price — they're what the message costs inside Plurel, where all five sit on one balance.

Do it in Plurel

1. Open the chat. It opens straight into a conversation.
2. Click the model name above the composer to switch between Claude Opus 5.5, Claude Sonnet 5.5, GPT-6 Astra, GPT-5.6 Luna or Grok 4.7.
3. Type your question. The credit cost for that model shows before you send, so there's no guessing.
4. For research, turn on web search in the chat (available on Claude Opus 5.5, Claude Sonnet 5.5, GPT-6 Astra and Grok 4.7) so the answer comes back with citations.
5. For a document instead of chat text, ask the model to produce it, or open the PDF tool directly (1 credit) — it saves a real PDF, spreadsheet or Word file to Document History.

Ask all three the same question in one chat

1. Open the chat and pick Claude Opus 5.5 from the model switcher.
2. Type your question and send it. Read the answer.
3. Click the model switcher again, choose GPT-6 Astra, and send the exact same question in the same thread. Astra will answer fresh, without being biased by Claude's wording, since each model only sees the thread's user messages and its own prior turns are what gets carried forward — the point is you get three independent takes without opening three apps.
4. Switch once more to Grok 4.7, send it again, and you'll have three answers stacked in one scrollback to compare line by line.
5. If one answer is clearly weaker, ask the strongest model to critique the other two — Opus and Astra are both good at this kind of comparison task.

This whole exercise costs whatever the three individual messages cost (around 4.5 credits for one Opus + one Astra + one Grok message), which is cheap insurance before you commit a longer task to one model.

Troubleshooting and tips

• If an answer feels generic or hedged, that's usually Luna or a quick model being asked a question it wasn't built for — switch to Opus or Astra for anything that needs judgment.
• If you need today's news or a stock price, don't use a model without search turned on; Grok 4.7 or GPT-6 Astra with web search are the right picks, not a base chat answer.
• If a long document comes back truncated, break the task into sections and ask the model to continue, rather than pasting the whole thing in one message.
• Benchmarks move fast. The "second place" read on Grok 4.7 noted above is one outlet's snapshot at launch, not a permanent ranking — re-check before you lock in a workflow for months.

For more on how reasoning-heavy models spend credits on "thinking" before they answer, see reasoning models explained, and for concrete Opus prompts, see Claude Opus 5 prompts for research, code and files.

There's no single winner here — pick Luna for speed, Sonnet for everyday writing, Opus for the hard stuff, Astra for agent-style file work, and Grok when the answer has to be from this morning.