A survey of online user experience priorities among ad buyers showed that out of the 283 questioned, 79% said that they place the highest level of importance on overall site/app experience as well as page load time. Other qualities respondents marked as “important” or “very important” were creative quality, content personalization/relevance, responsive design, number of ads, as well as virus and malware protection.

Source:
https://www.clickz.com/stats-of-the-week-ux-gets-an-f/101769/