I love festus.Festus Krex is my favourite dialogue provider.
"When life gives you lemons, go murder a clown."
"... his chocolate pate gives me the runs."
Urag gro-Shub's dialogue in the Arcanaeum, "Disrupt my Arcanaeum and I will have you torn apart by angry atronachs." Also, "You are now in the Arcanaeum, of which I am in charge. It might as well be my own little plain of Oblivion." Honestly, this is my favorite character in the whole of Skyrim, he's so well written; no wonder so many quests send you to him.