Verdict
Built from the measurements below
- Accuracy is too close to call: Gemini 3.1 Pro Preview scored 77.5% and Gemini 4 Argon 84.8% on the same 80 questions, a gap within what chance alone could produce.
- Gemini 4 Argon is 2.7× cheaper per question as billed ($0.0063 vs $0.017), reasoning tokens included.
- Gemini 3.1 Pro Preview generates text 1.8× faster: 124 tokens per second against 69.
Which should you choose?
Choose Gemini 3.1 Pro Preview for faster streaming. Choose Gemini 4 Argon for the lower cost per correct answer ($0.0074 against $0.022) and shorter outputs (about 558 tokens per question against 1,382). The widest subject gap is in law: Gemini 4 Argon answered 6 of 6 correctly, Gemini 3.1 Pro Preview 3 of 6. With so few questions per subject, treat this as a lead to test on your own prompts, not a result.
Accuracy gap -7.3 points (z = -1.18). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.