UPDATED JULY 29 — NEW DATA SINCE LAUNCH
● Opus 5 Arena.ai Frontend Code: #1 preliminary at 1,725 Elo (still accumulating votes)
● Grok 4.5 DeepsecBench: Price-performance winner — $5.60-$11/run vs Sol $56/run
● Grok 4.5 hallucination (new): Artificial Analysis confirmed doubled rate vs Grok 4.3 (25% → 54%)
● Price unchanged: Opus 5 $5/$25/M · Grok 4.5 $2/$6/M
● Who signs the pacing petition: Anthropic staff (Clark, Kaplan). No xAI equivalent.
Claude Opus 5 for: Writing quality, reasoning (ARC-AGI-3 30.2%), Arena #1 on frontend coding (blind user preference), voice with tool access, effort control (5-level toggle), and regulated industries where Anthropic's safety posture (FLI C+, RSP, petition signatories) matters.
Grok 4.5 for: High-volume coding at lower cost (60-76% cheaper), cybersecurity scanning (DeepsecBench price-performance winner at $5.60/run), live X data, and SuperGrok subscribers who want voice + coding in one plan. Validate hallucination rate on your tasks first — Artificial Analysis confirmed 54% (doubled from 4.3).
Last updated July 29, 2026. Related: Opus 5 Arena.ai #1 → · Grok 4.5 DeepsecBench →
⚖ Our Verdict
Opus 5 wins on Arena.ai Frontend Code (preliminary #1 at 1,725 Elo), writing quality, reasoning (ARC-AGI-3 30.2%), effort control, and safety posture (Anthropic FLI C+). Grok 4.5 wins on price (60-76% cheaper), DeepsecBench cybersecurity price-performance ($5.60 vs Sol $56/run), live data, and terminal tasks. Grok 4.5 hallucination rate confirmed doubled (54%) — validate before production.