I agree with Joachim Pense: the feature of Persian that has always stuck out for me is the back /ɑ/. That, in combination with the velars and palatoalveolars, make it sound… how do I come up with an impressionistic description? Passionate, actually. Kinda like German, which I love for its crunchiness, but with an extra /ɑ/, which makes it sound impassioned and earnest.