I much prefer the happy endings. Sometimes, however, a movie/anime does it right and has both. It is the sad ending but one that leaves you with a sense of hopefulness as opposed to just pure sadness. Saving Private Ryan or StepMom are examples of movies that accomplish this in my opinion. Of course, let us not forget that most movies do not have a sad or happy ending, they just have plot resolution (like an action movie or a thinking movie). Those types of films can still be good even though they do not draw on the strongest emotions of happiness/sadness.