Kinda hard to tell which would look best when they're not being worn, but to me, the gold one is kinda disgusting , like the colour is bad and the material is bad, it's kinda like a cheap version of Belle's dress from Beauty and the Beast (aaaah, I feel so mean, I'm so sorry <3 ) It could look awesome when on but it's just not something I like at all. The purple dress as a nice colour and shape and is more modern, so I like that one.
I honestly feel like I've seen dress A many time in different color same style. Dress B however is unique. I mean you could play up the whole golden bronze angel look. A nice gold shadow winged eyeliner a little bronzer and sparkles. If you curled your hair and wore it down. Added some gold heels and a bronze clutch you would be good to go. I can picture it already.