Sonnet 5.5 vs Fable 5.1: The Cheaper Model Won 10 to 4

One creator put Sonnet 5.5 against Fable 5.1 in three tests, 4 points per round (2 for quality, 1 for cost, 1 for speed):

Round 1: a stick-figure app that smashes any image. Close call. Sonnet 3, Fable 2. Round 2: a Rube Goldberg chain-reaction machine. Fable was faster, Sonnet’s looked better. 6 to 4. Round 3: a bug hunt in a real app, with a penalty for made-up bugs. Fable 21, Sonnet 85, at about 63% less cost.

Grain of salt: these are one creator’s tests, not a lab benchmark. Fable was stopped early in the bug hunt because of usage limits, and the bugs were graded by another AI.

The real takeaway: you don’t have to pick one. Let a top model plan and check the work, and let Sonnet do the heavy lifting.