I did a test last summer and never got around to posting the results.

My average muzzle velocities were (10 shots on +23C day, out of 18" bbl semi-auto):
-Velocitor 40gr CPHP:
1298.4 fps Std Dev:
36.3 fps
-American Eagle 38gr CPHP:
1217.2 fps Std Dev:
48.8 fps
-Federal 38gr CPHP:
1172.0 fps Std Dev:
10.2fps
-Win. Power Point 40gr CPHP:
1204.4 fps Std Dev:
13.9 fps
-Stingers 32gr CPHP:
1591.4 fps Std Dev:
19.7 fps
The Federals were the most consistent round-to-round and the Power Points were the most accurate. I did some expansion tests on water jugs (10shots of each) and I found the PP's were by far the most impressive at mushrooming.
Although they didn't get as big as the stingers, they still mushroomed pretty big! Not only did they expand explosively, but every single one had almost identical performance, unlike the next best Stingers.
Surprisingly, the velocitors were the worst and only one of 10 rounds managed to mushroom at all. They did have good penetration though.
The federals and AE were about even, with 7 of 10 of the AE's expanding decently vs 8 of 10 of the federals. They expanded to respectable sizes for small game hunting.
My money is on the velocitors as the all around, most potent round due to good velocity, excellent accuracy and massive expansion. They're also the best value IMO at around $27/brick.