Personally, my favorite happily-ever-after scenario is Bring Back Black. (Does anyone remember that old Veil of Possibilities challenge? It kills me that no one ever finished it and got Sirius back to the right 'verse!) That way we get most of the events of the series plus the happy ending (and as I said in another one of these posts, I'm a big sucker for reunion fic).

That said, I can read lots of different versions and be happy. Raising Harry (as long as it's not too cutesy), Sirius never went through the veil, total AU, meeting again in the afterlife...it's all good. :)