Bartz has fans. I agree he's pretty terrible (Vaan is actually far better and far less dull), but he has actual fans for whatever reason. Vaan just doesn't. It's a bit like some people hating Cecil, Squall, Tidus, Cloud, etc. Some dislike them, but at the end of the day every main character has a fanbase.
Except Vaan.
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Still smilin'
:>