You have already seen Slayers then? =) And you didn't mind Lina's temper I guess? : D
Besides this anime I would say Ghost in the Shell, Death Note and maaaaybe FMA. I don't know, it is always hard to pick favorites out of all of them. For example I like 5 Centimeters per Second and Voices of a Distant Star a lot, they are among my favorite romance anime; or The Wings of Honneamise, Perfect Blue, Princess Mononoke - ingenious movies, true works of art, putting anything on top of them doesn't feel right; Lucky Star and The Melancholy of Haruhi Suzumiya are my fav slice of life series, it is not as serious as the things I've mentioned above, but I liked both a lot, even re-watched bits and pieces. So what should I do : D