Answer: Design look 

From CB Insights report on fast growing FinTech apps:

Stanford’s BJ Fogg asked 2,684 people to write about how they assessed the credibility of various websites — design look was mentioned in nearly half of all the comments, significantly more than any other factor.

It turns out it's even more important for fintech applications:

Design matters in fintech because design is central to a website’s credibility. Design can build up trust or break it down very quickly. It can burden users with excessive information and friction that ruins the user experience.

Here's a chart showing the top 10 factors: 

Questions:

• Why do you think that website design is so important for people? 
• How does "Accuracy of Information" compare to "Design Look" when it comes to credibility of websites? Do you agree with that? Why or why not?
• What are the website features that matter most to you in judging credibility? Why?
• What is an example of a website you visit that has a great design? Poor design? Explain your answer.

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