If we’re talking fan favorites, popular choices include Charizard, Greninja, Blaziken, Sceptile, Swampert, and Infernape. Greninja and Charizard regularly show up near the top of fan discussions, while Swampert and Blaziken are often praised for their in-game strength.
Ultimately, there’s no official “best” starter—it depends on whether you value design, nostalgia, story-mode usefulness, or competitive battling.