Julietta. Well, he's less annoying and more INCREDIBLY creepy.
Renge has one of the most annoying voices known to man. Combine this with the fact that she is incredibly whiny and raises her voice a lot and you get prime screeching irritation.
More generally anyone who makes a lot of pretentious speeches. I mean if they're good it's one thing but if they're just half baked and trying and failing to be deep it's another. Go back to arguing about power levels already GOD. mad
Kogoro Mori in Detective Conan
Reimi in Bamboo Blade
Evangeline in Negima
Kenichi and Nijima in History's Mightiest Disciple Kenichi
The entire casts of Haruhi Suzumiya and Black Butler. I can't stand any of 'em.