I think the anime has already lost its touch in the dub version since it parted ways with 4kids back in 2006.
Also, I really hate Ash's new (PUSA) voice, because it's not as memorable as his old voice. In fact, it has made him sound way over the top.
I have a lot of cartoon characters that are very annoying:
Sam/Clover/Alex/Mandy/Britney (Totally Spies)
Gwen (Ben 10: Alien Force)
All the characters from Disney Channel cartoons (e.g. Phineas and Ferb)
Any characters from Chaotic
Sentinel Prime (Transformers Animated)