First of all, both of their universes are different from each other. Red is expected to catch all the Pokemon in his region, and in Ash's universe you don't just go straight to fight the Elite 4; you have to fight several other trainers of varying experience, strength, and battle knowledge.

And let's face it; neither are as great as they are made out from the fandom. Red has skill, but he lacks personality. Silent protagonists are cool when done well (eg. Claude from GTA III), but there really wasn't much going with Red aside from being a caricature of the player. Even in Origins, his character wasn't much other than being the typical Pokemon trainer aiming to be a master (then again, that is mostly due to the fault of the pacing). As for Ash, he has the heart and humor, but he lacks consistency. One saga he's all hot stuff, then next region he gets a mind reset. He mostly suffers from a case of bad writing and plot armor.

And yeah, maybe Manga Red might be the superior, but let's be honest; how much of the Pokemon fandom actually reads the manga?