First, buy some FMJ or JHPs from Montana Gold, Precision Delta, or Zero (see Powder Valley for Zero Bullets).
Next, what is your basis for efficiency? Velocity/grain of powder? Maximum velocity? The powder that Lyman thinks may be most accurate for your bullet weight?
I find real "efficiency" with AA2 and Competition. Other excellent 9x19 powders low- to mid-range loads are AA5, 231/HP38, Zip, and N320.
If you want velocity and accuracy, look to Silhouette and HS6. Silhouette is my first choice for accurate and near-max loads in 9x19, 9x21, 38 Super, and .40S&W.
True Blue and Longshot can generally get you above factory velocity without over pressure.
Before all the new powders, Herco was generally the powder that would give you the best accuracy and near-max pressure and velocity. I still use it quite a bit.
Now, what do want your loads for?