Claude Sonnet 4.6 vs GPT-4.1 vs Gemini 2.5 Flash: which wins JSON extraction?

We had a question: for structured-output tasks where you just need clean JSON back, which frontier model wins on a cost/quality basis? The answer matters because most production LLM features aren't writing poetry — they're extracting fields from emails, summarizing tickets, classifying intents. Boring, structured, repetitive. The kind of work where overpaying by 5x for marginal quality gains is just a tax on your margins. We benchmarked. Setup Task: extract {sender, intent, urgen...