This study investigates the mobility trends of indium-gallium-zinc oxide (IGZO) thin-film transistors over a wide range of fabrication conditions, from amorphous to crystalline phases. By utilizing machine learning potential (MLP) to generate 70 distinct IGZO structures, we analyze electron mobility while taking into account structural disorder and electron scattering mechanisms. Our findings reveal that mobility peaks at the transition from amorphous to nanocrystalline phases, and then, as more ordered, crystalline structures emerge, the mobility decreases sharply due to the distortion of polyhedron of indium-oxygen in well-ordered regions. These results offer critical insights into optimizing the fabrication conditions for high-performance IGZO devices by identifying the ideal structural phase for achieving maximum mobility.