Of course every game is bound to have some annoying characters. For me they are... Yeah Allers, Juhani, Aria, Liara, Old Tegrin, Bizzaro Anders, I also kind of don't like Female Shepard (but, I know lots of people love her)
I just really hate the voice acting on female Shepard. Man Shepard is sort of monotone, but female Shepard has this really fake sounding put-on butch tough guy voice. She sounds phoney and unnatural. To me, it gets annoying fast.
Yeah, after talking to Allers more, I liked her some after her story about being raised on a colony that was attacked.