Gameplay-wise, Wynne. Sure, she has a habit of running into the fray for no discernable reason and catching an unfortunate case of the dead, and I usually end up having to use poultices every five seconds anyway, but she helps keep some sort of flow going. Sometimes.
Which is more than can be said for any other character that isn't me.
Story-wise, though, definitely Alistair. He's the most fun to talk to.
Also, were I a girl (or perhaps a gay dude) I might also mention that he is incredibly sweet and that the scene with the rose actually made me coo audibly.
... Which... which I'm not saying I did.
Just, you know. In those circumstances, I would.
Maybe.
...
I'm heterosexual. [http://tvtropes.org/pmwiki/pmwiki.php/Main/HaveIMentionedIAmHeterosexualToday]
I wish he existed so I could ravish him