Verdict
Built from the measurements below
- Accuracy is too close to call: Muse Spark Open scored 77.5% and Muse Wonder 78.8% on the same 80 questions, a gap within what chance alone could produce.
- Muse Spark Open is 4.7× cheaper per question as billed ($0.0045 vs $0.021), reasoning tokens included.
- Muse Spark Open generates text 1.3× faster: 220 tokens per second against 175.
- Muse Spark Open starts answering sooner: 0.5 s to the first token, against 16.1 s for Muse Wonder.
Which should you choose?
Choose Muse Spark Open for the lower cost per correct answer ($0.0058 against $0.027), faster streaming, a quicker first token, open weights you can run yourself and more hosts to choose from on OpenRouter (6 against 1).
Accuracy gap -1.2 points (z = -0.19). We call a winner only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.