Personally;
Funniest:
"Imperials think we should obey to their laws... Pffft" - Sound of Pffft is the best sound ever.
- "I never head of Tiber Septim killing dragons."
"That's cause there were no any dragons then, idiot.
"Let me guess, someone stole your sweet roll." - One with the most cocky voice
Most annoying:
"Have I seen you talking to Sven?" - I kill him, every time I start a new game. Every time. Unless I want some archery training.