Quick Answer
Claude and ChatGPT with data opt-out offer the best privacy among major providers.
Detailed Answer
Anthropic (Claude) has strong privacy commitments and does not train on user data by default. OpenAI allows you to opt out of training via settings. Google (Gemini) collects more data through its ecosystem. DeepSeek stores data in China with weaker privacy guarantees. For maximum privacy, use API access instead of web interfaces, enable data opt-out settings, and never share credentials or PII with any AI.
Find Your Own Answer
The best way to decide is to try them yourself. Council lets you compare multiple AI responses to the same question.