Mobile strategy company Xtreme Labs has analyzed customer reviews from the Apple App Store and the Google Play Store and found RBS Citizens and USAA to have the highest-rated apps.

The company looked at app reviews between May 18 and June 25 for the top 53 U.S. banks, as ranked by total assets.

RBS Citizens' mobile apps get high marks from both iOS and Android users. The two highest ranked banking apps in Apple's App Store during the period studied were the bank's Citizens Bank Mobile Banking, which received an average 4.5 stars and 93% favorable reviews, and Charter One Mobile Banking, which reaped 4 stars and 91% positive comments. Citizens Bank Mobile Banking for Android also came in second in Google Play, with 4.5 stars and 97% good reviews.

USAA's Android app was the highest rated app in Google's marketplace, with 4.6 stars and 95% favorable reviews. American Express's Android app came in third, with 4.4 stars and 91% favorable

According to Xtreme Labs, accolades for top ranking apps tend to be about frequent updates, specific bug fixes according to customer feedback, and ease of use, with users often describing the app as "everything you need" in a mobile app for "someone on the go."

Banks whose apps fared the worst in customer reviews — M&T Bank on the Android side; People's United Bank, PNC and SunTrust on the iOS side — were bashed for things like a dashboard not loading properly or the app being merely a link to the mobile website.