Well I can't really call the ending of Eva "happy"... but that's one of a few exceptions on my list to the "happy" rule as far as I can tell. When I say that I prefer happy endings over sad ones I was thinking more of series like Code Geass, Deathnote, and Cowboy Bebop whose endings I didn't really like. Overall I think all of those three are fairly good series, but they don't really suit my tastes so they're not on my favorites list.