Optical flat-fielding systems, such as field-mapping or integration-based beam shapers, are used to transform nonuniform illumination into uniform illumination. Thus, flat-fielding paves the way for imaging that is independent of position within a field of view and enables more quantitative analysis. Here, we characterize and compare three systems for homogenizing both widefield and multifocal illumination. Our analysis includes two refractive field-mapping beam shapers: PiShaper and TopShape, as well as one integration-based: Köhler integrator. The comparison is based on figures of merit including ISO-standard values, such as the plateau uniformity and edge steepness, transmission efficiency, stability of the beams along propagation and multifocal intensity, pitch, and point width. By characterizing and comparing existing beam shapers, we facilitate the choice of the appropriate flat-fielding solution and increase their accessibility for different applications.