Choosing the Right LLM for Your Agent
GPT-4, Claude, Llama, Mistral—how do you pick? Here's a practical guide to choosing the best LLM for your agent.
The Major Options
GPT-4 / GPT-4o (OpenAI)
- Best for: Complex reasoning, tool use, general tasks
- Pros: Best overall performance, great function calling
- Cons: Expensive, rate limits, closed source
Claude 3.5 (Anthropic)
- Best for: Analysis, safety-critical tasks, long context
- Pros: 200K context, strong safety, great writing
- Cons: Higher cost for Sonnet/Opus, less tool ecosystem
Llama 3 (Meta)
- Best for: Self-hosting, cost-sensitive, privacy
- Pros: Free, open source, runs locally
- Cons: Requires infrastructure, lower quality
Mistral
- Best for: European data compliance, efficiency
- Pros: Strong performance/price ratio, open weights
- Cons: Smaller ecosystem than OpenAI
Decision Framework
- Budget? Low → Llama/Mistral, High → GPT-4/Claude
- Privacy? Sensitive data → Self-hosted Llama
- Complexity? Simple tasks → Cheaper models
- Speed? Real-time → GPT-4o-mini or Haiku
Cost Comparison (per 1M tokens)
| Model | Input | Output |
|---|---|---|
| GPT-4o | $2.50 | $10.00 |
| GPT-4o-mini | $0.15 | $0.60 |
| Claude 3.5 Sonnet | $3.00 | $15.00 |
| Llama 3 (self-hosted) | ~$0.50 | ~$0.50 |
Recommendation
Start with GPT-4o-mini for prototyping. Scale to GPT-4 or Claude for production. Consider self-hosting when costs exceed $500/month.