I love Farsi – it’s mellifluous and haunting. I really like Siwi too (a Berber language spoken only in the Siwa Oasis near the Egypt-Libya border) which is also very sing-song.
It’s funny, though, because so much seems to depend on who is speaking! I lived in Poland, and some Poles sound like they are chewing gravel when they speak, whereas some speak in such a beautiful, soft cadence that it turns my legs to jelly. Now I’m wondering how much this correlates with my perception of the speaker.
I also like Egyptian Arabic. It’s by no means a beautiful language, and it often sounds (especially as spoken in Cairo) as though people are shouting at each other, when in fact they are simply having a conversation. It is, however, slangy, adaptable, and full of rich, earthy expressions. My favorite one translates as “If hair was important, it wouldn’t grow out of your arse” (I’m bald)!