Decision boundary
Do not start with which model is absolutely stronger. Start with the boundary: cost, context, speed, quality, ecosystem, or supply stability.
- GPT-5.4 Nano is worth checking first when the GPT-5.4 family, 400K context, and text+image+file->text capability match the job.
- Grok 4.20 is worth checking first when the Grok family, 2M context, and text+image+file->text capability match the job.