What this covers
A task-by-task decision sheet for picking the right AI assistant for office work — meetings, email, docs, slides, sheets.
Key tools and concepts:
- ChatGPT: OpenAI’s chat product (Plus / Pro tiers).
- Claude: Anthropic’s chat product (Pro / Max / Team / Enterprise tiers).
- Gemini: Google’s chat product plus Workspace AI (Google AI Pro / Ultra).
- Microsoft Copilot: Microsoft 365 Copilot, an assistant that lives inside Outlook, Word, Excel, PowerPoint, and Teams.
What each is actually best at for office work
The four products look similar on the homepage and price page; their day-to-day behavior is not.
ChatGPT (Plus / Pro)
What: OpenAI’s chat product. Plus ($20/mo) gives you GPT-5 / o-series reasoning models, Custom GPTs, Canvas, file upload, image generation, and light Code Interpreter. Pro ($200/mo) adds heavier reasoning, longer context, and Sora video.
Office strengths:
- General-purpose writing across tones and formats.
- Custom GPTs that codify a recurring office prompt (the same intern, every time).
- CSV and spreadsheet analysis via Code Interpreter — it runs Python on your file.
- Image generation for slides, social, and one-off decks.
- Canvas for collaborative editing of a long doc or code file.
Sample office tasks:
- Build a Custom GPT named “Weekly Status Rewriter” that takes raw bullets and returns a team-update in your house format. Reuse it every Friday.
- Drop a 100k-row CSV into a chat and ask:
Find the top 5 quality issues by region.
Return a table plus a bar chart.
Use the column "defect_rate" for ranking.Loses on: real-time Google Workspace integration (Gemini wins); deep Microsoft 365 hooks (Copilot wins); pure long-context document reading (Claude wins).
Claude (Pro / Max / Team / Enterprise)
What: Anthropic’s chat product. Pro ($20/mo) gives you Sonnet-class models with a 200K-token context window, file uploads, and Projects (per-project knowledge base). Max ($100-200/mo) adds more Opus usage. Team and Enterprise add shared Projects and Connectors.
Office strengths:
- Long-document reading — drop in a whole 200-page PDF in one prompt.
- Polished long-form writing, with careful editing and rewriting at low hallucination rates.
- Artifacts for code, HTML, and diagrams that render inline.
- Projects to keep a meeting series, product spec, or brand voice in one place — every new chat in that Project inherits the context.
Sample office tasks:
- Attach a full 80-page board pre-read and ask:
Summarize the pre-read in one page.
Then list the 6 questions a non-executive director should raise.- Set up a Project called “Q3 Planning” with all OKRs, the last six weekly statuses, and your team’s brand voice. Every chat inside the Project already knows the context.
Loses on: live web search (less native than ChatGPT or Perplexity); image generation; deep Workspace or M365 integration.
Gemini (Google AI Pro / Ultra)
What: Google’s chat product plus Workspace AI. Pro ($20/mo) gives Gemini 2.5 Pro and Gemini inside Gmail, Docs, Drive, Sheets, and Slides. Ultra ($250/mo) adds Veo 3 video, longer Deep Research, and more compute.
Office strengths:
- In-Workspace assistance — Gemini reads your Gmail thread for context, expands a Docs outline into a draft, builds Sheets formulas, and drafts Slides decks.
- Deep Research output drops straight into a Google Doc with citations.
- Veo 3 for short-form video; NotebookLM Audio Overviews to turn source docs into a podcast.
Sample office tasks:
- In Gmail, on a long thread: “Draft a reply that politely declines the meeting and proposes a Q4 follow-up.”
- In Sheets:
@Gemini build a formula in column C that returns
the rolling 4-week average of column B.Loses on: Custom-GPT-style automation (ChatGPT wins); long-form polished writing (Claude wins); developer tooling.
Microsoft Copilot (M365 Copilot)
What: Microsoft’s M365 assistant, $30/user/mo for businesses. Lives inside Outlook, Word, Excel, PowerPoint, Teams, and Loop, with access to your tenant’s email, files, and meetings.
Office strengths:
- Outlook: “draft a reply, formal tone, two paragraphs.”
- Word: “rewrite this section more concise” or “add a 1-paragraph executive summary at the top.”
- Excel: “add a column with YoY%” or “highlight rows where revenue dropped more than 10% MoM.”
- PowerPoint: “build a 10-slide deck from this Word doc.”
- Teams: meeting recap with action items, decisions, and speaker attribution.
Sample office tasks:
- After a 1-hour Teams meeting: “What did marketing commit to and by when? List owner + due date.”
- In Excel on the monthly revenue tab:
Highlight rows where revenue dropped more than 10% MoM.
Add a column with YoY%.Loses on: anything outside the M365 tenant; image and video generation; raw reasoning depth (lags ChatGPT Pro and Claude Max on hard problems).
One-line picker
- Live in Google Workspace → Gemini.
- Live in Microsoft 365 → Copilot.
- Lots of writing and long documents → Claude.
- Maximum flexibility, Custom GPTs, Code Interpreter → ChatGPT.
Who this is for
Knowledge workers deciding which 1-2 AI subscriptions actually deserve a slot.
When to reach for it
When you’re evaluating ChatGPT Plus vs Claude Pro vs Gemini Advanced vs Microsoft Copilot for daily office work.
Step by step
- List your weekly office tasks. Group them: writing, reading, summarizing, calculating, scheduling, communicating.
- For each group, run the same prompt across the two most plausible candidates. For writing: ChatGPT Custom GPT vs Claude Project. For long-doc summaries: Claude vs Gemini Deep Research. For Sheets / Excel formulas: Gemini in Sheets vs Copilot in Excel. For meeting recaps: Copilot in Teams vs ChatGPT (manual transcript paste). Compare on accuracy, speed, format fit, and copy-paste ease.
- Match tools to your dominant environment, not to a feature list. If 80% of your day is Gmail / Docs / Sheets, default to Gemini. If 80% is Outlook / Word / Excel / Teams, default to Copilot. Then add ChatGPT or Claude as your “thinking” tool on top.
- Stack-test: pick your top two, use them in parallel for two weeks. Track which one you reach for first.
- Drop the one you barely opened. Renew the survivor.
- Set a quarterly re-check — model and feature parity changes fast.
Recommended workflow
List tasks → cross-tool prompt test → match by dominant workflow → 2-week parallel trial → drop the unused → quarterly recheck.
Common mistakes
- Subscribing to all 4 — you’ll use 2
- Picking by feature list instead of by your real tasks
- Never re-evaluating — the leader from a year ago may not be today’s
FAQ
- Can free tiers carry me?: For light office use, yes. Heavy use (50+ chats/week) benefits from one paid tier.
- M365 Copilot worth it?: Only if you live inside M365 daily — otherwise ChatGPT Plus is cheaper and more flexible.
- I use both Google and Microsoft.: Pick by which one owns your hairy stuff: calendar, shared files, ongoing projects. Buy that AI first. The other side can wait a quarter — it usually catches up in features anyway.