1 "내 가장 좋아한 노래 이야" (이야 is wrong. 좋아한 sounds strange) 2 "내 가장 좋아하는 노래야" = It's my best-loved song (more natural) * 내가 가장 좋아하는 노래야 = It's the song I like the best (best) We say 내가 좋아하는 노래 much more than 나의 좋아하는 노래 because "내가" with the particle is always much clearer than the less distinct "나의" or "내" (Japanese uses 나의-style construction in this case, but not Koran). When the phrase doesn't involve a verb, 나의/내 is commonly used though. So "my favorite song" can be said like 나의/내 애창곡, where 애창곡 is a hanja-based noun corresponding to "favorite song". 좋아한 is the attributive form of 좋아하다 in the past tense. It evokes the sense of the past or a result of some action. It doesn't work very well in this case because 좋아하다 is not an action or event. 좋아하는(that I like) or 좋아했던(that I used to like) sound the most natural. 야 attaches to syllables with no ending consonant(노래야), while 이야 comes after those with one (사람이야).