Verdict: Gemini 3.8 Flash at high thinking effort wins on cost and turnaround; Claude Opus 4.6 stays the pick for long-horizon agentic persistence and very large single outputs. If you are asking which LLM is best for coding on cost and turnaround, the answer today is Gemini 3.8 Flash at high thinking effort. In our own controlled run, it matched Claude Opus 4.6 exactly on machine-checked instruction following while finishing in roughly a third of the wall time and costing a fraction as much pe...