If I want hardware to be removable I use polysulfide, 3M 101 or Boatlife Lifecaulk. If I want the bond permanent I use 3M 4200/5200. If it has to be white and I want it removable, I use Sikaflex 291 LOT. Sikaflex is a polyurethane like 4200, but not quite as tenacious. Polysulfides in white tend to yellow over time.