Let's agree to disagree.
Yes EQ is not going to make one headphone sound like another. I am not advocating that position.
It varies. Fankly, this whole quest for neutrality is insane without a reference. One man's neutral is another man's Grado!
I am 100% certain that neither the LCD-3 or TH-900 would be classified neutral. Believe it or not, from a purely FR perspective the Sony MDR-V6 is probably closer to "neutral."
Totally neutral would be a flat frequency graph. Which one has a flatter frequency graph?