Frequently asked questions
Which LLM is best at reasoning in 2026?
Right now Gemini 3.1 Pro, GPT-6 Astra and Claude Fable 5 lead (graded on GPQA Diamond, Humanity's Last Exam and MMLU-Pro plus an overall task grade). Best open-weight: DeepSeek V4-Pro. Best budget pick graded A or better: Qwen3.7 Flash ($0.03/$0.13 per 1M tokens).
What is GPQA Diamond?
GPQA Diamond is the hardest 198-question subset of GPQA, a set of graduate-level science questions written by domain experts. Experts in the field score about 65% and skilled non-experts about 34% even with web access, so it still separates strong models.
What is Humanity's Last Exam?
Humanity's Last Exam is a benchmark of about 2,500 expert-written questions across many subjects, built to stay hard after older benchmarks saturated. Scores are much lower than on other tests, which makes differences between top models visible.
Should I use a thinking model for everyday tasks?
Usually not. Thinking modes use many more output tokens and add seconds of delay. Keep them for hard problems such as proofs, multi-step planning and difficult debugging; for ordinary questions and writing a standard model is cheaper and just as good.
Which open-weight LLM reasons best?
DeepSeek V4-Pro, Kimi K3 and Kimi K2.6 lead the open-weight models for reasoning right now. The cheapest model graded A or better is Qwen3.7 Flash ($0.03 in / $0.13 out per 1M tokens).