Best AI for Complex Reasoning
Which AI reasons best under pressure? Ranked across 11 challenges: contracts, architectures, ethics, history, business, and multi-stakeholder dilemmas.
13 challenges20 models#1 Claude Fable 5
How Complex Reasoning rankings are computed
20 models tested across 13 complex reasoning challenges. Composite score: 30% Rival Index, 20% task coverage, 20% challenge-scoped duel performance, 15% recency, 15% tier. Deduplicated by product line. Claude Fable 5 leads at 92.9/100. Drawn from Rival's open dataset of 21,000+ human preference votes.
Rival's Pick
#3 Rival IndexAnthropic flagshipToo close to call
Head-to-Head
Full Rankings
20 models#
Model
Coverage
Index
Price
Score
Challenges13
Related