The answer to your question can vary through each Anime. For me the Death Note ending I felt happy, they finally caught Light/Kira, however for FMA I had mixed feelings for it as I was happy some lived but sad that some were gone. However both were tremendous Anime. It just depends on the Anime and your connection to the characters, plot, and the show in general. If I watch an Anime that is good and has a good ending and sums everything up, I guess it will leave me happy. I don't think I can vote though as the question can have a lot of answers.