Most likely A for me. It's like seeing a new person for the first time - you can't help but gather information and take in a first impression, even if it turns out that you're wrong later on. An icon says a lot about what the creator has in mind for the spirit of the series - whether it's an important character, pose, or moment. It's kind of an interesting summary of a story, in my opinion. It also definitely boils down hugely to personal style and preference, though.
Also opening my current icon to thoughts/opinions/simple style criticism. Thanks!

(Outer Spaces is a bit of a slice-of-life project on life, differences, and inspiration, painted against a fantasy backdrop.)