Hey, you’re right, actually.
The best attitude, personal experience, nets +15 human disposition over all three phases combined; the worst, ignorant, nets -18. It’s clearer if I reorder them by net effect:
Ignorant / -6 / -6 / -6 / -18
Indifferent / -3 / -3 / -3 / -9
Hysterical Fear / -1 / -1 / -1 / -3
Paranoid / 1 / 1 / 1 / 3
Educated or Informed / 3 / 3 / 3 / 9
Personal Experience / 5 / 5 / 5 / 15
And on quarantine, the best (strict) is only +9, while the worst (none) is -12:
No Quarantine / -4 / -4 / -4 / -12
Standard Quarantine / -1 / -1 / -1 / -3
Advanced Quarantine / 1 / 1 / 1 / 3
Strict Quarantine / 3 / 3 / 3 / 9
In almost every other set of choices, the overall effect across all three phases nets to zero – except for Location, and even there the best human option (Core) is merely equal to the worst (Void), at +6 and -6 respectively.
So, if you’re looking at the Infection as a whole, you can choose almost anything you want and still dial up or down the difficulty for the human side at will simply by being careful about Attitude and Quarantine. But the options you choose for other choices have tremendous impact on how each Phase goes: In general, most choices favor the Vaylen during Infiltration (presumably to keep the game from ending prematurely!) and Human during Invasion, but there’s a great deal of variation. Each option can be seen as having a kind of spectrograph composed of its net Infiltration, Usurpation, and Invasion scores.
Which, again, is much clearer when you graph it. Pending (possible) posting to the Downloads section, I can email the Excel file to anyone who want it on request.