French or Spanish seems a fine choice because either way there's a high chance you will use it to good purpose. [Now wait; are you asking for advice ? Definitely go for Spanish so you can use it. You could learn it faster that way; paving your way for a second latinate language such as French, Portuguese, Italian, etc. Besides, aren't there Spanish beauties, too ? ]
I've tried answering similar "what language" threads before, but this is a great chance to talk about something different. How about doing one totally different, unrelated from any language I know ?
For a truly exotic language, I'd go for one of the language isolates or one of an isolated language group. Basque would be interesting, although it's supposed to have many loans from Spanish/French (?)... I hear Basque has some following among the Japanese.