Oooh -- Aziraphale and Crowley. It's very simple:
* The eternal teenager inside me roots for Crowley. I don't think I'll ever outgrow tall, dark and handsome bad boys who aren't really bad at heart.
* The book lover inside me roots for Aziraphale. I mean, how could any book lover not root for the owner of a bookstore?
And of course, however slick I may find this year's screen adaptation, there is absolutely no question that David Tennant and Martin Sheen are Crowley and Aziraphale.
Then again, by way of decidedly more than a side note, I also root for Agnes -- far and away the most kick-ass of all the book's female characters.
(Task: In Terry Pratchett’s and Neil Gaiman’s Good Omens, who do you root more for: Aziraphale or Crowley? Or another character? (And in each case: why?))