Ulundil - yeah, I know he's the token constantly optimistic Bosmer. (even though technically he's an Altmer)

He freaks me out with his excessive niceness.

Maybe he's a Thalmor spy?!
Esbern isn't bad, even though he doesn't cooperate with you when you choose P'nax' side. But hey, he's a quiet old man who likes his peace, so it'd be too much effort for him to go against the hyperactive and bossy Delphine (he'd be slaughtered). Besides, he does explain his side of the bargain quite understandably, although I still don't agree with it. But we don't have to agree just to be pals. And I suspect he's doing his best to mellow out Delpine towards me, as I'm still able to at least sleep and take the loose items from Sky Haven Temple. I also gotta admit, his voice is nice and soothing. ^^
Gilfre from Mixwater Mill is also good to my character. Well, not like you can really get much from her, but it's pleasant to go see her every time I pass by.
On that same note, Erik The Slayer always greets me very excitedly whenever I see him at Sky haven Temple. Makes my return there very enjoyable, before Delphine ruins it again.
Tolfdir also seems to be genuinely nice, helping you wherever he can and explaining your archmage duties just because he can and wants to. In contrast, the Greybeards seem to be likable fellows too, but I always get this slight feeling they're doing it because they can gain from it.
Oh, and I love the Khajiit caravan trader who frequents Whiterun, his smile is simply too adorable!