Urban livability faces significant challenges due to traffic congestion, noise, and vehicle emissions. Electric buses offer a promising solution to reduce noise and tailpipe emissions in cities. However, their limited range, constrained by battery capacity, can hinder operational flexibility. As an alternative, plug-in hybrid electric buses (PHEB) and hybrid buses (HB) provide a more versatile option by combining zero-emission capabilities with conventional diesel engines. Their efficiency depends on battery capacity and the strategic allocation of electric drive sections along routes. Yet, existing electric drive assignment systems remain suboptimal, as they do not fully exploit the potential of hybrid propulsion. The significance of electromibility is highlighted in this work, by analyzing the broader environmental benefits and the impact on urban quality of life of these two main technologies. Unlike previous approaches that primarily emphasize energy efficiency, this work develops optimized strategies for maximizing electric driving distance while minimizing overall emission. The problem is formulated as a multi-objective optimization, tackled using a state-of-the-art evolutionary algorithm and the existing GreenK heuristic. These methods enable exploraing different electric drive distribution scenarios while accounting for real-world traffic conditions and route topography. Results demonstrate that the electromobility technology used significantly impacts on sustainability, hybrid buses producing higher emission levels (covering 17,9% less distance with the electric motor), but avoiding the need of any charging infrastructure. In either case, HB or PHB, the optimized electric drive strategy can significantly reduce emissions and enhance the efficiency of public urban bus networks, contributing to more sustainable public transportation systems.