I took some more readings with the Jett-Stream only and some 12" props.

Temperature: low 80s
Humidity: medium
Fuel: Omega 10% nitro, castor blend
Props: All APC
Muffler: Jett-Stream

12-4: 15,000
12.25-3.75: 14,500
12-5: 14,600

The 12-4 looks a little small.
The Jett-Stream looks like a good thing for the 3D people who like the 12.25-3.75 wide blade.
I didn't have an APC 12-6, but I'll bet it would be good, too. Probably be the best sport prop.