お金を拾いました。今日は何かいいこと（ あるようです / ありそうです ）。
We got into a bit of a dilemma over this in class. Which one do you guys think is right in this case?
EDIT: We actually went over the questions in class, and the answer is ありそうです, according to the official worksheet solutions, which was somewhat unexpected, as this seems like more of a job for ようだ, considering that the evidence is not (solely) visual in nature.
The only explanation we could think of, was that そうだ provides a weaker level of evidentiality than ようだ, and so it conveys a sense of superstitiousness better.
But even if the case is that そうだ sounds more natural, we couldn't grasp why ようだ would be incorrect, if it is. (We've already encountered one or two slight errors in the textbook, but I'm assuming that isn't the case here.)