Of Marvel's long-standing super heroes, I'd have to say the two I've never had a real interest in were the Hulk and Thor. I have a pretty decent comic collection, but it probably includes less than 20 from each character's main title. For Thor, I never really got into the myth- and deity-based adventures. I did really like the recent movie, and today's selection I, Whom the Gods Would Destroy would serve well as an introduction to the character for new fans if it weren't out of print and 25 years old.
IWGWD as I shall have to call it is an 1987 graphic novel that has Thor at his angsty best. I'm not being snarky here, as the theme of the story is the dualism and conflict entailed by Thor trying to reconcile what it means to be immortal with his alter ego Don Blake's mortality. As Blake, Thor faces mortality up close every day as a surgeon with the inevitable risk of losing patients on the operating table. At the same time, however, he recognizes a joy and excitement of mortal life that the endless, interminable repetition of immortality can't begin to match. Thus, Thor begins to spend more and more time as Blake, much to the dismay of Odin, who sentenced him to live as a human to teach him humility. Lady Sif enters the picture as Thor's long-time love interest, but she's disdainful of his life as Blake and can't understand why he would ever want to spend time with mere mortals.
Thor's wrestling with mortality and immortality really is the plot of IWGWD; there are no super-villains, evil gods, demons, or really any fight scenes at all: quite unusual for a Marvel comic!* It doesn't come across as boring however, though perhaps a touch ham-handed here and there. Still, one gets the sense that the writers wanted to tell a serious story to try get deeper into Thor's personality and the inner conflict driving the character at that point in continuity. It's good stuff, and successful on at least one indicator: it makes me want to read more Thor comics.
* Okay, Lady Sif gets into a bit of a bar brawl and Thor has a montage where he stops some crooks and puts out a house fire, but still!