The short answer
- Your email and files are in Google Workspace: try the Gemini that comes with your Workspace plan before paying for anything else.
- You run on Microsoft 365: start with Copilot Chat, which is included with eligible business plans, and buy the paid Copilot license only for people who'd use it inside Word, Excel and Outlook every day.
- You want the strongest general assistant for writing and reading documents: pick ChatGPT or Claude. Try both free on the same real task and keep the one you prefer.
What each one costs
| Tool | Plan | Price | Worth knowing |
|---|---|---|---|
| ChatGPT | Plus | $20/month | One person. Monthly billing only. |
| ChatGPT | Business | $25/user/month, or $20 billed annually | 2-user minimum. No training on business data by default. |
| Claude | Pro | $20/month, or $17/month billed annually | One person. Includes Projects and Claude in Microsoft 365. |
| Claude | Max | From $100/month | For people who use it all day. Most offices don't need it. |
| Claude | Team | $25/seat/month, or $20 billed annually (standard seat) | For 2 to 150 people, with project sharing, SSO and central billing. |
| Google Gemini | Workspace Business Standard | $14/user/month, billed monthly | Includes business email and storage, with Gemini in Gmail and Docs. Google lists 16% off with a 1-year commitment, and new-customer promotions may be lower. |
| Microsoft Copilot | Copilot Chat | No extra cost with eligible Microsoft 365 plans | Web-grounded chat, plus Copilot in Outlook. |
| Microsoft Copilot | Microsoft 365 Copilot Business (add-on) | $21/user/month, paid yearly | Copilot inside Word, Excel and PowerPoint. Microsoft lists $18 for the first year on purchases through December 31, 2026. |
What it adds up to for a 5-person office
Using the prices in “What each one costs,” with everyone on a seat:
| Option | Monthly cost for 5 people | What you get |
|---|---|---|
| ChatGPT Business | $100 billed annually ($125 month to month) | A shared AI workspace. Email and files stay where they are. |
| Google Workspace Business Standard | $70 billed monthly (less with a 1-year commitment) | Email, storage and Gemini together. Only a saving if you'd pay for email anyway. |
| Microsoft 365 Copilot Business add-on | $105 paid yearly ($90 in the first year on the current offer), plus your Microsoft 365 plan | Copilot inside the Office apps your team already uses. |
You rarely need a seat for everyone on day one. Start with the one or two people who write the most.
A one-week test
- Pick one real, repeat task, such as replying to a customer email or summarizing a document.
- Do it in two tools on free plans, with the same instructions and files.
- Keep the one whose drafts needed less fixing.
- Set it up properly with your rules and examples. The ChatGPT setup guide works for any of these tools.
Sources
Prices are list prices in US dollars from each vendor's own page. Every price and plan detail in this guide was re-checked against the live vendor page on October 21, 2026. Vendors change prices and plans often, so confirm on their page before you buy. I don't get referral fees from any tool mentioned in this guide.