We comparatively evaluated two types of image-reconstruction algorithms in two types of single-shot phase-shifting digital holography techniques to investigate which algorithm is more suitable for high-quality and instantaneous three-dimensional imaging. Two types of image-reconstruction algorithms were proposed for each single-shot phase-shifting interferometry so far. One generates multiple phase-shifted holograms from the recorded single hologram by utilizing interpolation and derives the complex amplitude of the object wave by applying the calculation of phase-shifting interferometry to the multiple phase-shifted holograms. The other does not use interpolation but applies the calculation of phase-shifting interferometry to the neighboring pixels in the recorded hologram to derive the complex amplitude. We experimentally evaluated the qualities of the image reconstructed by the algorithms in each single-shot phase-shifting technique. It was clarified that the former algorithm is more effective for high-quality imaging free from the unwanted images in single-shot technique using an array of optical elements. In single-shot technique using spatial carrier, although the latter algorithm is able to reconstruct a brighter image for wide area than the former, spatial-filtering technique is needed for removing the conjugate image.