Claude Opus 5.5 (max) vs Grok 4.7
Should you write with Claude Opus 5.5 (max) or Grok 4.7? On this page the only thing that changes is the model. Both wrote their own version of the scripts behind 10 of my What's AI videos, five drafts per script, and four judges (three LLM judges from three model families plus Jev, a typed judge from TypeSafe) scored every draft blind, with my finished script as the reference. Claude Opus 5.5 (max) leads overall, 90.8 to 87.6.
The verdict
Claude Opus 5.5 (max effort) is #1 and Grok 4.7 is #32, and Opus wins every metric. But look at where: Length Adherence is the big one, about twenty-six points, while everything else is within about three. Grok writes well, it just rarely lands on the requested length. It costs about twenty-seven cents a script against about $2.75 and takes under eight minutes instead of seventeen. If you're willing to cut or pad by hand, Grok gets you most of the writing for a fraction of the price.
Pick Claude Opus 5.5 (max effort) when the script has to land on length and be ready to record.
Pick Grok 4.7 for strong writing at a fraction of the price, if you'll fix the length yourself.
How to read these numbers
Overall vs Elo. Overall is the weighted rubric score. Elo compares each model's five-draft average with every other model's, script by script, and counts gaps inside run-to-run noise as draws, so it rewards winning often and can disagree with overall.
Reading the Elo intervals. Each 95% range comes from resampling every model's recorded run scores on each task and re-ranking. Comparing these separate ranges does not test the Elo gap between two models: far apart is strong evidence, and overlap isn't a tie. The tasks stay fixed, so the ranges say nothing about new tasks (the long version).
Metric by metric: where the gap comes from
Blue is Claude Opus 5.5 (max), orange is Grok 4.7, and the solid bar takes the metric. The weight under each name is how much it counts toward the overall. Weighted by how much each metric counts, Length Adherence does the most to put Claude Opus 5.5 (max) ahead: it leads there by 26.2 points. If you care about one thing, say voice or length, go straight to that row.
Cost, speed, and consistency
Quality is half the decision. The other half is what each script costs you, how long you wait, and how often you get a bad draft. The lead has a price: Claude Opus 5.5 (max) costs about 10x as much per script as Grok 4.7.
| Claude Opus 5.5 (max) | Grok 4.7 | |
|---|---|---|
| Overall / 100 | 90.8 | 87.6 |
| Writing Elo | 2683 | 2143 |
| Score spread across drafts (± overall std) | 1.290 | 2.490 |
| Cost per script (USD) | 2.746 | 0.267 |
| Avg time per script (min) | 17.1 | 7.7 |
| Open weights | No | No |
Green wins the row, and for spread, cost and time, lower wins. Cost is one script at recorded list prices, uncached and without judging, so your real bill will differ. Spread is how much the overall score moves across a model's drafts, and time is the average time to get one accepted script, retries included.
Want the script-by-script detail? Full scorecards: Claude Opus 5.5 (max) · Grok 4.7. The whole scoring pipeline is on the methodology page.
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