Whichever one feeds reliably in your pistol. If that is hardball, so be it - unless you want to pay to have it throated (and tested with a particular load). Second factor would be accuracy of course.
I don't have a .38 Super, but I lean towards heavier bullets in hollow points these days, out of concern over insufficient penetration. In .45 that means 230-grainers, or 9mm 147-grainers (and some controlled expansion 125+grainers). Any current offerings from Federal, Winchester, or Remington would be my first stop for test ammo.
Even if I had a pistol that would only perform with hardball in terms of reliability and accuracy, I wouldn't feel disadvantaged carrying just that. In all cases, I load spare mags with hardball as it happens.