In terms of specialization, Mario lacks a distinct advantage compared to the other characters. His balanced abilities make him less appealing to me, as Toad's slightly weaker jump can be compensated for, and Peach and Luigi excel in both horizontal and vertical jumping, respectively.
super mario bros
Overall, Luigi feels the most consistent for my playstyle. While Toad and Peach may offer convenience for specific levels, there are no significant incentives to using Mario over the other characters.