Ichigo Kurosaki from Bleach is a very easy choice. I really liked the first 60 or so episodes of the show, and enjoyed the manga for a little while after that, but it took a horrible downwards spiral after that and to me Ichigo was the personification of the drivel that the series turned into.
Not only did he very quickly become a boring invincle hero, he got there by doing absolutely nothing. He just gets new strength as the plot demands, with almost zero work on his part, easily beating people who have trained for literally thousands of years. The worst moment I remember is when he's fighting Grimmjow in Hueco Mundo for the second time, and he's more or less holding together but not managing to do any damage in retaliation, and then Inoue shouts at him and he remembers that actually he wanted to win and not lose and suddenly he's strong enough to catch a head on attack bare handed and basically cut Grimmjow in half.
Then there was the final time that he fought Ulquiorra, and after his superpowered hollow form virtually destroyed Ulquiorra, Ichigo asks him to do the same damage back to him because "That's not me" and "It won't be even unless we're in the same state". Let's not forget that before Ichigo transformed into a hollow he couldn't put a scratch on Ulquiorra and had just had a head-sized hole blown in his chest with no effort whatsoever. And Ulquiorra's main power is regeneration of body parts, which Ichigo doesn't have (without transforming into an unthinking and uncontrollable monster anyway). And even ignoring both of those facts, this isn't a sporting competition, the whole reason he's there is to rescue his friend that Ulquiorra kidnapped, which he's going to find seriously hard to do if he's missing an arm and a leg (and y'know, dead, because he's nowhere near as strong as Ulquiorra at this point when not in hollow form).
I'm gonna stop there before I start going off topic with all the other things I hate about the show, but those are the ones that came to my mind first.
Not only did he very quickly become a boring invincle hero, he got there by doing absolutely nothing. He just gets new strength as the plot demands, with almost zero work on his part, easily beating people who have trained for literally thousands of years. The worst moment I remember is when he's fighting Grimmjow in Hueco Mundo for the second time, and he's more or less holding together but not managing to do any damage in retaliation, and then Inoue shouts at him and he remembers that actually he wanted to win and not lose and suddenly he's strong enough to catch a head on attack bare handed and basically cut Grimmjow in half.
Then there was the final time that he fought Ulquiorra, and after his superpowered hollow form virtually destroyed Ulquiorra, Ichigo asks him to do the same damage back to him because "That's not me" and "It won't be even unless we're in the same state". Let's not forget that before Ichigo transformed into a hollow he couldn't put a scratch on Ulquiorra and had just had a head-sized hole blown in his chest with no effort whatsoever. And Ulquiorra's main power is regeneration of body parts, which Ichigo doesn't have (without transforming into an unthinking and uncontrollable monster anyway). And even ignoring both of those facts, this isn't a sporting competition, the whole reason he's there is to rescue his friend that Ulquiorra kidnapped, which he's going to find seriously hard to do if he's missing an arm and a leg (and y'know, dead, because he's nowhere near as strong as Ulquiorra at this point when not in hollow form).
I'm gonna stop there before I start going off topic with all the other things I hate about the show, but those are the ones that came to my mind first.
