The thing that turned me off the anime wasn't really Ash's annoying personality, but much of the series didn't make much sense. They look like forgot that Pokémon rules existed at all and that made stuff like Pokémon using moves they don't learn, Pokémon having more than 4 moves (cough cough snorlax cough) and just many other wrong stuff in general.
Also, Ash's plot armor. Why. Its like they forgot to give him any redeeming qualities and were like "Hehey! Look! The power of the main character!" Making him win battles he definitely SHOULDN'T have won (still salty about when Team Rocket actually won fair and square but then plot armor appeared and then "oh no! Bewear took them before they could actually win, what a shame!") or even losing battles he should've won, mainly the ones in the Pokémon League, so that they could keep the series up indefinitely! (Looking at you, gen 4 and gen 6's league.)
Speaking of plot armor, there's also the fact that Ash has died 7 different times, however he's still alive. Its weird, I know.
Honestly, Team Rocket is the only thing saving the series for me.