Gradient formation of Poml is a key regulator of cell cycle and cell growth in fission yeast (Schizosaccharomyces pombe). A variety of models to explain Poml gradient formation have been proposed, a quantitative analysis and comparison of these models is, however, still missing. In this work we present four models from the literature and perform a quantitative comparison using published single-cell images of the gradient formation process. For the comparison of these partial differential equation (PDE) models we use state-of-the-art techniques for parameter estimation together with model selection. The model selection supports the hypothesis that buffering of the gradient is achieved via clustering. The selected model does, however, not ensure mass conservation, which might be considered as problematic.