The short answer
For most business chatbots, any current model from OpenAI (ChatGPT's GPT models), Anthropic (Claude) or Google (Gemini) is good enough. The differences that matter show up on your own questions: how often each one answers correctly from your content, how it handles questions it cannot answer, how fast it replies, how well it writes in your customers' languages, and what it costs at your volume.
Model lineups and prices change every few months, so this guide does not rank specific versions. It shows you what to compare and how to test it yourself, which takes an afternoon and gives you an answer that is actually about your business.
What actually differs between the three
| Factor | Why it matters for a chatbot | How to judge it |
|---|---|---|
| Grounded accuracy | The bot should answer from your knowledge base, not from general knowledge | Score answers to your real questions as correct, partly correct or wrong |
| Handling the unknown | Saying "I don't know" beats a confident wrong answer | Ask questions your content does not cover and check for honest fallbacks |
| Instruction following | Tone, length, refusals and format rules in the system prompt | Check whether replies stay on brand and inside the rules |
| Speed | Visitors notice a slow first word more than a long answer | Measure time to first token with streaming on |
| Languages | Quality varies by language and model size | Test in every language your customers use |
| Cost | Small, fast models are often enough for FAQ-style support | Estimate tokens per conversation x monthly volume |
How to test them on your own conversations
- Collect 50 real questions from support tickets, chat transcripts and sales calls, including a few the bot should not answer.
- Use the same setup for every model: the same knowledge base, the same system prompt, the same temperature.
- Score every answer as correct, partly correct, wrong or appropriately declined. Note anything off-brand.
- Time the replies with streaming on, from send to first word.
- Repeat in each language you support, with a native speaker scoring.
- Price it using each provider's current rates and your real message volume.
For a broader view, independent public leaderboards compare general model quality and speed, and are updated as new models ship - use them to shortlist, then decide on your own questions. Our guide to preventing chatbot hallucinations covers the prompt and fallback setup that matters more than model choice.
Checking current prices
All three providers price by tokens (roughly, pieces of words) in and out, with large differences between their flagship and lightweight models. Prices change often, so check them at the source: OpenAI API pricing, Anthropic pricing and Gemini API pricing.
To estimate, multiply the average tokens in a conversation (your system prompt and knowledge snippets plus the visitor's messages and the replies) by your monthly conversation count. For FAQ-style support, a lightweight model usually costs a small fraction of a flagship one and is often accurate enough; test before paying for the bigger model.
Rules of thumb by scenario
- High-volume FAQ and order questions: start with a lightweight, fast model from any of the three and move up only if accuracy falls short.
- Nuanced support where wrong answers are costly: test the providers' flagship models and favour the one that declines most honestly when the answer is not in your content.
- Sales and lead qualification: conversational tone matters; judge transcripts for how natural and on-brand they read.
- Multilingual customers: test every language with native speakers; rankings differ by language.
- Strict data requirements: check each provider's data retention and training policies, or use a self-hosted model.
Common mistakes when choosing a model
- Choosing on a general leaderboard alone. A model that tops a public ranking can still be worse on your products, your jargon and your languages. Shortlist from leaderboards, decide on your own questions.
- Blaming the model for a content problem. Most wrong answers come from missing, outdated or contradictory source pages. Fix the knowledge base before switching models.
- Paying for a flagship model you do not need. Routine questions rarely need the largest model. Start small and upgrade the conversations that need it.
- Testing without a fallback. Every model will meet questions it cannot answer. Judge how each one declines, and make sure your bot hands off to a person.
- Ignoring speed. A brilliant answer that takes many seconds to start loses visitors. Turn streaming on and measure the time to the first word.
- Testing once. Providers update models regularly. Re-run your 50-question test when you switch versions or every few months.
Privacy and data handling
Before sending customer conversations to any model provider, check three things in their current terms: whether API data is used to train models (business API terms commonly exclude it by default, but confirm it), how long requests are retained, and where data is processed. If you operate under strict rules, such as healthcare or finance, keep sensitive personal data out of the chat entirely, or use a self-hosted model so conversations never leave your infrastructure.
Whatever you choose, tell visitors they are talking to an AI assistant and link your privacy policy before asking for personal details. Our chatbot GDPR guide covers consent and retention in detail.
Using more than one model
You do not have to pick one forever. Many teams use a fast, cheap model for routine questions and a stronger one for complex or high-value conversations, and switch when a better model ships. Conferbot connects to OpenAI GPT, Anthropic Claude, Google Gemini, DeepSeek and 17 other providers, including self-hosted models through Ollama, so you can change the model behind a bot without rebuilding the flow.
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About the Author
The Conferbot team writes about building, deploying, and improving AI chatbots.
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