ChatGPT, Claude, Gemini or Copilot: How to Choose Your AI Assistant

How to compare them fairly

The golden rule: same prompt, same day, all four tools.

• Models are updated frequently. If you compare on different days, you can't tell whether a difference comes from the tool or from a new model version.
• Create a free account on each tool, keep four browser tabs open, and send the identical prompt at the same time.

And define your expectations BEFORE reading the answers: write down 3 elements you expect to see in a good response. It's the step almost nobody does, and it's what gives you real judging criteria.

Don't judge by format alone, either. The class used the prompt "How can I improve my team's productivity?":

A better prompt can make formats converge, so ask "what did I expect?" rather than "what looks nicest?".

Tool ≠ model

The tool (the app/product) is not the same as the model (the LLM running underneath). Model names reflect the date of the class and change often:

Copilot has an intermediate layer called Prometheus, which orchestrates OpenAI's model together with Microsoft's context. For enterprise use it accesses your emails and OneDrive to answer with your own information; for personal use it uses the Bing search engine when it needs up-to-date data.

Gemini, meanwhile, is integrated inside Google Workspace apps. In the standalone chat, you have to bring that context in yourself.

Fast models vs. reasoning models

A fast model answers immediately with what it already knows or finds online. A reasoning model first plans: it asks what steps are needed, executes them, and only then answers. That technique is called chain of thought ("think step by step"). It used to require that phrase in the prompt; reasoning models now do it automatically.

The trade-off: reasoning is slower and usually more expensive. Each tool has its own selector:

• Gemini: 2.5 Flash (fast) vs. 2.5 Pro (reasoning, math, code).
• Claude: Sonnet (efficient for everyday use) vs. Opus 4.1 (complex challenges).
• ChatGPT (paid): GPT-5 with thinking variants and Pro.
• Copilot: toggle between GPT-4 and GPT-5.

The 5-step method

1. Identify a real task from your work.
2. Write a clear prompt with role, focus, context and limits.
3. Test it on all four tools on the same day.
4. Evaluate results using the criteria you defined before reading them.
5. Choose the model that best fit that task.

Repeat the method whenever you have doubts, since models keep changing.

Practical tips

• Test for one month, then pay only for the tool that solved the most. If two tools cover different problems, paying for both is justified.
• Don't be swayed only by native integration (Copilot with Microsoft, Gemini with Google): first solve the problem well, then check how well the tool connects to your stack.
• Learn the interfaces. The key is knowing where to switch the model, upload files and write the prompt; everything else changes constantly.