There is no single best model for everyone. Define your task first, then test candidates with the same data and evaluation criteria.
Step one: define the task
Writing, code completion, long-document analysis, and image understanding have different requirements. Note the input length, output format, whether citations are required, and the acceptable error rate. Do not treat a public aggregate leaderboard as your business result.
Step two: prepare a test set
Choose 10–20 representative, de-identified examples from real work, including simple, difficult, and boundary cases. Write down what a passing answer means for each example; human review and programmatic rules can work together.
Step three: compare four dimensions
- Quality: Does the answer follow instructions, avoid invented facts, and get key fields right?
- Latency: Does the experience meet interactive needs at normal and busy times?
- Cost: Include input, output, caching, tool calls, and the provider’s complete billing rules; use the provider’s current prices.
- Constraints: Check context, rate limits, regions, data-processing terms, and support.
Step four: move from a pilot to production
Validate on a small scale with non-sensitive data, recording each task, result, and cost before expanding. Models, prices, and access channels can change, so important workflows need continuing tests.
Turn broad goals into acceptance criteria
For example, “a good summary” can mean: it includes the source’s key conclusions, contains no incorrect numbers or added facts, and is under 200 words. For code, check unit tests, dependency changes, and security boundaries. Clear criteria keep comparisons from becoming personal preference.
What matters for different tasks?
- Customer-service drafts: Does the answer cite real rules and decline to guess when the materials have no answer?
- Code assistance: Does it pass tests, avoid unnecessary dependencies, and keep secrets out of the code?
- Document analysis: Does it preserve numbers, qualifications, and sources?
- Structured extraction: Are fields complete and correctly typed, including missing values?
See the model family map for background, and use the evaluation template for your own comparison.