Anthropic: Claude Opus 4.8 vs SpaceXAI: Grok 4.3
As of 2026-10-19: On the un-leaked meo benchmark, Anthropic: Claude Opus 4.8 is the more accurate of the two (84.9% vs 66.5%), while SpaceXAI: Grok 4.3 is cheaper per correct answer. Compared on accuracy, Effective Value (π), cost, speed, context, and pricing β all from the un-leaked meo benchmark.
| Metric | Anthropic: Claude Opus 4.8 | SpaceXAI: Grok 4.3 |
|---|---|---|
| meo rank | #7 | #29 |
| Accuracy | 84.9% | 66.5% |
| π index (top=100) | 12.1 | 1.7 |
| $ / correct answer | $0.0459 | $0.0127 |
| Seconds / correct | 21 | 20 |
| Context window | 1M | 1M |
| Price out ($/M) | $25.00 | $2.50 |
| Open weights | β | β |
Green = the stronger value on that metric. π indexed to the leaderboard top = 100.
Frequently asked questions
Is Anthropic: Claude Opus 4.8 better than SpaceXAI: Grok 4.3?
On accuracy, Anthropic: Claude Opus 4.8 leads (84.9% vs 66.5%). On Effective Value (π), which weights accuracy for deep agentic chains, Anthropic: Claude Opus 4.8 is ahead. βBetterβ depends on whether you optimize for accuracy, cost, or speed.
Which is cheaper, Anthropic: Claude Opus 4.8 or SpaceXAI: Grok 4.3?
SpaceXAI: Grok 4.3 costs less per correct answer ($0.0127 vs $0.0459), which already accounts for accuracy β a cheap-but-wrong model is penalized.
Anthropic: Claude Opus 4.8 vs SpaceXAI: Grok 4.3 for agentic / coding work?
For long multi-step chains, rank by Effective Value (π): Anthropic: Claude Opus 4.8 leads here. Accuracy compounds across steps, so the more accurate model usually wins deep agentic work even if it is slower.
Full pages: Anthropic: Claude Opus 4.8 (Anthropic) Β· SpaceXAI: Grok 4.3 (xAI). More: all comparisons Β· full leaderboard Β· methodology.