GPT-5.6 Sol (ultra) vs Muse Spark 1.3 (thinking)
Head-to-head on the Towards AI writing benchmark: same 10 real YouTube scripts, five runs each, scored blind by a three-family judge panel. GPT-5.6 Sol (ultra) leads overall, 88.0 to 82.6.
The verdict
GPT-5.6 Sol (ultra) has the stronger current result: #16 at 2155.9 Elo and 87.97 overall, compared with Muse Spark 1.3 (thinking) at #49, 1699.2 Elo, and 82.63 overall. Their 95% Elo confidence intervals do not overlap, which supports the directional ordering (2115.80–2190.10 and 1653.10–1736.10). GPT-5.6 Sol (ultra) has its clearest metric edges in Length Adherence (91.90 versus 63.88) and Visual Cue Quality (88.55 versus 75.93). Muse Spark 1.3 (thinking) does not lead an individual published metric in this pairing. At the measured run mix, GPT-5.6 Sol (ultra) costs $0.143 per article versus $0.041 for Muse Spark 1.3 (thinking); Muse Spark 1.3 (thinking) is the cheaper route. Both are closed-weight routes. On the current automated evidence, GPT-5.6 Sol (ultra) is the stronger default; Muse Spark 1.3 (thinking) remains a defensible choice when its specific strengths, price, or deployment profile matter more than the headline rank.
Pick GPT-5.6 Sol (ultra) when you prioritize the stronger current board result, length adherence, and visual cue quality.
Pick Muse Spark 1.3 (thinking) when you prioritize lower measured cost.
Metric by metric
Blue bars: GPT-5.6 Sol (ultra). Orange bars: Muse Spark 1.3 (thinking). Same 0–100 scale; the bold bar wins that metric.
Everything else that differs
| GPT-5.6 Sol (ultra) | Muse Spark 1.3 (thinking) | |
|---|---|---|
| Overall / 100 | 88.0 | 82.6 |
| Writing Elo | 2156 | 1699 |
| Run-to-run spread (± overall std) | 1.450 | 2.770 |
| Cost per script (USD) | 0.143 | 0.041 |
| Avg latency (s) | 195.5 | 78.0 |
| Open weights | No | No |
Full scorecards: GPT-5.6 Sol (ultra) · Muse Spark 1.3 (thinking). How scoring works: methodology.
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