I think the firefly would probably appear brighter because of the higher contrast in the black. The vanilla is more of a softer/cleaner look, where the fire has more contrast...harsh blushing, etc.

I like both, but I'm planning to combine all three genes (pastel/vanilla/fire), so I didn't need to buy both. The decision was pretty easy for me...pastel vanillas cost half as much as fireflies, look very similar, and they have the distinct advantage of being able to make super vanilla pastels

But again, it's not like I'm choosing one over the other...I already have a few female fires, so I'll be trying to make fire vanilla pastels as soon as possible. And I don't exactly see myself selling any female fireflies. lol