Most Helpful Girl
Besides English and Finnish? Probably French. It might not be as useful as other languages but I've been struggling to learn it for too long.
Most Helpful Guy
I'd say Chinese. Not for any practical reasons (like job opportunities), but simply because I think it would (until job opportunities and such are important) be a decent enough troll (due to its uselessness) - until the Chinese take us over and I'm the one laughing at my peers!