Best Speer

[AZXD]

Numbers are all theoretical.
Call speer and ask which will perform better as it relates to expansion. Then get some ballistics gel or a few water jugs and see if they might be telling you the truth.

The difference between the two weights will be the depth of the bullet unless the HP cavity is designed for each weight.

So skip the stopping power stuff as it is mostly marketing hype.
Unless you know what it takes to develop the designed expansion of each bullet, you're spinning wheels.

Call Speer and find out what their designed impact potential is for proper expansion. Tell them you are interested in just the bullet and not ammo.

Translation = If both specimens require 1300 fps to achieve proper expansion, neither will perform to its potential unless you can load it hotter than factory.

Take a look at this for some insight.

I don't own a 40, but looking at this terminal 40 s&w, I'd probably skip the Speer Gold Dot as it appears there are better performing bullets available.
ETA: That data might be a little old and there might be even better stuff available than what is listed. Testing is the only way to know for sure. BUT, check out the PMC JHP Starfire!!! It expands better in 9mm than the Speer does in 40