Short answer: None of them. You’re better off starting with the least-expensive model that can do the job. The reliability of your own company's data, workflows, and integrations plays a far bigger role than the model you choose.

OpenAI's GPT-5.6 family includes Sol, Terra, and Luna with tiered pricing from $1 to $5 per million input tokens, launching globally on July 9, 2026.

Short answer: None of them. You’re better off starting with the least-expensive model that can do the job. The reliability of your own company's data, workflows, and integrations…