Klasse and Zaino are great products that have a proven track record.
Blackfire is in the process of proving itself and with a few exceptions, people have been very pleased with it.
But to answer your original question, a lot of Autopians here might choose the look of Blackfire if all three products were masterfully applied and layered on three dark colored cars and lined up together. This is just my impression as I haven't tried BF yet (planning to BF a friend's black Lexus this weekend).
I have tried Klasse and Zaino, and between the two I prefer the high optics and gloss of Zaino. Klasse is a very close second, but I'd have to give the nod to Zaino. I love the way it glows at night (which I don't get with Klasse or carnauba). I also like the fact that Zaino (w/ZFX) seems to have the least amount of issues with things like hazing, cure time, rapid diminishment in shine or slickness and dust attraction.
As for the customer service, Sal is probably the only person (affiliated with a car care products company) I have talked to that hasn't tried to feed BS to me.