I love Vann because I get to be one of the most annoying characters of all time. And by that I mean annoying to the populace in the game. I get to go around town shouting idiotic propaganda! Awesome!
"I'm Captain Basch! Don't listen to Ondore's lies!"
That was a fun part of the game. Vaan isn't so bad. Most games have this sort of character to take away from the seriousness of the storyline.