My hypothesis is if the pills are put in stomach acid, then the gelcaps will dissolve the fastest, because gelcaps are just gelatin capsule that hold the liquid inside. So when the liquid is released it will be absorbed faster than the other pills.
I base my hypothesis on Gel Caps or Coated? Pick the Right Pill, page 2 that says, “Soft, flexible gelatin capsules hold liquid-which may be absorbed more quickly than regular pills”.