PLD gets an extra 34 VIT on base stats while WAR/DRK gets an extra 24. All three tanks have identical base VIT scores while WAR/DRK just have 10 more STR.

I consider a ratio of 0.35/0.65 the ceiling value [it could be a little higher but I was only working at 0.05 resolution and 0.40 is too high) for making slaying accessories undesirable against slaying accessories by virtue of secondary stats. As you noted 0.25/0.75 is a crossover point at which tanks are identical to where they were so applying the extra vitality base stat (only applicable if 1 STR + 1 VIT = 1 AP). The target value will remain 779 AP.

• 0.35/0.65 - 772.15 [P], 765.65 [W/D]
• 0.34/0.66 - 775.66 [P], 769.06 [W/D]
• 0.33/0.67 - 779.17 [P], 772.47 [W/D]
• 0.32/0.68 - 782.68 [P], 775.88 [W/D]
• 0.31/0.69 - 786.19 [P], 779.29 [W/D]
• 0.30/0.70 - 789.70 [P], 782.70 [W/D]
• 0.29/0.71 - 793.21 [P], 786.11 [W/D]
• 0.28/0.72 - 796.72 [P], 789.52 [W/D]
• 0.27/0.73 - 800.23 [P], 792.93 [W/D]
• 0.26/0.74 - 803.74 [P], 796.34 [W/D]
• 0.25/0.75 - 807.25 [P], 799.75 [W/D]

You have 12 combinations of racial stats. Base stats are 17+modifier so we'd only be concerned with the +0 to +6 for each race.

• Wildwood Elezen : +2 Str, +1 Vit [AP Loss]
• Duskwight Elezen : +3 Str, +2 Vit [AP Loss]
• Midlander Hyur : +4 Str, +3 Vit [AP Loss]
• Highlander Hyur : +6 Str, +5 Vit [AP Loss]
• Plainsfolk Lalafell : +1 Str, +1 Vit [Neutral]
• Dunesfolk Lalafell : +0 Str, +0 Vit [Neutral]
• Sun Seeker Miqo'te : +4 Str, +3 Vit [AP Loss]
• Moon Keeper : +1 Str, +0 Vit [AP Loss]
• Sea Wolf Roegadyn : +5 Str, +6 Vit [AP Gain]
• Hellsguard Roegadyn : +3 Str, +4 Vit [AP Gain]
• Xaela Au Ra : +6 Str, +3 Vit [AP Loss]
• Raen Au Ra : +0 Str, +1 Vit [AP Loss]

In all these cases, except Xaela, the loss and gain of AP will be less than 1.