Any language can sound sexy - it's all in the delivery.
At the beginner level, I'd have to say French is the harder langauge simply because of its pronuciation. If you can't pronounce correctly what you're trying to say, then that is a huge stumbling block.
The genderfication of all vowels is an absolute pain in the arse for both languages (der/die/das or le/la), and for most (all?) other non-English European languages.
Because English is spelt properly? It is one of the most illogical and irrational languages in pronunciation...
The apparently illogical and irrational nature of English is merely an example of the sheer brilliance of the people who invented it (that is, the English). What better way to expose the deception of the would-be spy who wishes to persuade an English gentleman that he, too, is a member of The Greatest Club on Earth? Merely ask him to say 'Loughborough', 'Leicester', 'Belvoir' or 'Uttoxeter' out loud.
Then mock him mercilessly as you blindfold him, offer him a cigarette and show him what you think of his inept attempts to speak God's own language.