Gemini 3.1 Pro vs GPT-5.4: I Ran Both on the Same 500 Tasks — Here's Which Won (And It Wasn't Close on Cost)

Gemini 3.1 Pro just became the best value in AI APIs. It matches GPT-5.4 on most benchmarks while costing 20-40% less. But benchmarks are benchmarks — I wanted to see how they compare on real work. I ran both models on 500 identical tasks across 4 categories and tracked quality, speed, and actual cost. Here's the raw data. The Test Setup 500 tasks total: 150 coding, 100 reasoning/math, 150 document analysis, 100 creative writing Identical prompts sent to both models Quality scor...