There are other, better-designed conlangs than Esperanto. Nobody speaks them, sure, but nobody speaks Esperanto either. And if we're going by popularity, might as well pick English anyway.
Personally though, I prefer Ido over Esperanto.
Esperanto is so easy it can be learned in negative time.
https://en.m.wikipedia.org/wiki/Propaedeutic_value_of_Espera....