I think Jeff is a good example of a story that could be great, had it been proof read. Clearly, the popularity of the character indicates that the writer did something correctly. I think it's worth looking into where the story failed and where it succeeded
Had potential, was bland, got popular because it was one of the og's, and became horribly cringe and has armies of fangirls. People think he can beat characters like thanos becuase they are blinded by their attraction to his cringy fanart that isnt even the original picture, which depicts him as a pretty ugly boi.
I don't really care for him tbh, the fanbase is what gets me but it is what it is.