Claude Fable 5 and GPT-5.6 Sol have reignited the battle for the top AI model in 2026, both offering native multimodal capabilities and advanced coding agents. Fable 5 is a Mythos-class model focusing on efficient reasoning by optimizing the tokenizer and output length, making it a workhorse task-completion expert, while GPT-5.6 Sol focuses on price-to-performance. Both ship with 1M-token context windows and support document, image, and text modalities, but neither supports audio natively. Fable 5 costs $10 per million input tokens and $50 per million generated output tokens, while GPT-5.6 Sol costs $5 per million input and $30 per million output tokens, with an effective price about half that of Fable. Anthropic optimized Fable 5 to run at 85 tok/s, more than twice as fast as GPT-5.6's 41 tok/s, significant for latency-sensitive applications. Benchmark results show neither model dominates: Fable 5 scores 62% on GDPval-AA v2, 27% on 𝜏³-Banking, 85% on Terminal-Bench v2.1, 60% on SciCode, 53% on Humanity's Last Exam, 93% on GPQA Diamond, 49% on AutomationBench-AA, 63% on IFBench, 51% on EnterpriseOps-Gym-AA, and 94