Best OpenAI primary source: OpenAI compare models. Official OpenAI model comparison page. Use it before swapping OpenAI models in coding, agent, or product workflows.
Best Claude primary source: Claude choosing a model. Official Anthropic model-selection guidance. Use it to compare speed, capability, and cost across Claude model families.
Best multi-provider catalog: OpenRouter models guide. OpenRouter catalog for comparing model families across providers. Use it when you need a broad view before testing prompts yourself.
Model selection needs tests, not vibes
Frontier model comparisons change constantly, and generic leaderboards rarely match your product. The right process is to start with official model docs, choose two or three candidates, and test them on your actual tasks.
Use OpenAI, Anthropic, Gemini, and OpenRouter docs to understand current capabilities and constraints. Then run your own evals for quality, latency, cost, tool use, structured output, and failure behavior.
Do not migrate because a model is famous
A stronger model on paper can be worse for a workflow if it is slower, more expensive, weaker at structured output, less reliable with tools, or harder to operate within your system. Model choice is an engineering and product decision.
The best resources for this topic are primary sources and repeatable tests. Blog posts and screenshots can be useful for discovery, but production migration should depend on current docs and your own task set.
Recommended courses and resources
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The AI Engineer Roadmap
Free tutorial · Matt Pocock · Beginner to intermediate
You want a guided path through core AI concepts, model selection, the AI engineering mindset, evals, and techniques for improving LLM-powered apps.
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OpenAI model guide
Model docs · OpenAI · Beginner to advanced
You need to choose between GPT-5.5, GPT-5.5 Pro, GPT-5.4 mini, GPT-5.4 nano, reasoning levels, tool support, and cost-sensitive API paths.
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Using GPT-5.5
Guide · OpenAI · Intermediate
You need the current OpenAI guidance for migrating to GPT-5.5, prompt shape changes, and tool-heavy workflow behavior.
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GPT-5.5 prompting guide
Guide · OpenAI · Intermediate
You want the official prompting adjustments for GPT-5.5 instead of reusing older GPT-4 or GPT-5 prompt habits unchanged.
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OpenAI reasoning model guide
Guide · OpenAI · Intermediate
You need to understand when internal reasoning is useful for coding, scientific work, agents, and harder multi-step tasks.
