What is a happy ending, anyway? There's not an accepted definition. This is especially true when you consider different temporal eras, cultures, countries. Some would say as long as the protagonist is alive at the end of the story, it's a happy ending.
I think the whole happy ending issue exemplifies the art versus entertainment dichotomy in fiction. In art, anything can happen. In entertainment, people want to be entertained; often this means they want and expect a happy ending. Fiction falls somewhere along this spectrum. I would say literary fiction is closer to the art end of the scale. Genre fiction, including speculative fiction, tends to fall closer to the entertainment end of the scale.
Where do the Electric Spec Editors fall in terms of their preferences? There are certain conventions in a particular culture and we editors are subject to them along with everyone else. As convention says all characters must be fully fleshed out now, more ambiguous endings are considered more sophisticated, better.
But you're in luck. To decipher what we really think (rather than what we claim) you can check out thirteen years of endings for yourself at Electric Spec.
What's your preference?