I hate happy endings.
I really do.
They usually feel forced, and unrealistic. Obviously in some settings, that's not entirely a bad thing, after all, I EXPECT a High Fantasy setting to have a happy ending. But I generally like doing the unexpected. Tragedy defines characters better than happy endings would. A happy ending leaves that character's future, essentially, open. It leaves them undefined at the end, and with no true defining point, the memory of them kind of fades.
But if it is a tragic ending, or an ending where they receive what they want, but generally at a horrible price such as their own life, that DEFINES who they are, it defines what they will do, and how they react to the future will make them change as a person. I find tragedy inspires change, and change inspires interest.