On the old question of syllable count - it doesn't actually work for English as a language. Not all syllables are of equal weight, so it's more important for the stresses to come in the right place for the melody. As for rhyme - assonance will do quite well! But most important of all is for the melody to work with the lyrics and for both to actually mean something to either the singer or the listener, but preferably both.
As for perfect lyrics ...where to start? So many to choose from down the centuries, and they're still being written.