I really enjoy Boethia's Calling. I brought "Erik the Slayer" up to Sacrifical Orb to give him a taste of what Skyrim is really like!!!! Shiiiiiiiiitt......he calls him Erik the "Slayer"? How 'bout a taste of the Blade of Sacrifice to welcome your non-adventurous ass!!!! hehehehehe!!!
My favorite Daedric artifact is probably the Oghma Infinium, since it's pretty much automatic 2-3 levels and it isn't even hard. Second is Spellbreaker, just because the idea of that is awesome. Since many players of Elder scrolls are fairly biased towards Sheogorath and Hircine right now, since they have had DLC centering entirely on them, I will pick another (my top favorite is Sheogorath), namely Peryite. Kind of a random choice I know, with him being the weakest Daedric prince and all, but I found it hilarious that his followers are diseased people who barf at you as their main attack. It's also interesting that you commune with him by inhaling drugs XD
I have to say, I'm having a hard time choosing. Sheogorath and I had a pretty normal (for me) conversation. He was a bro. But Molang Bal made me crack up. Namely, because he had the priest pledge him his soul, then was like "FINISH HIM!" Which I did. I don't even use maces that often...