“Customer service and speed of transactions – those are both outstanding scores for credit unions,” said David VanAmburg, managing director of the ACSI. “This is clearly the hallmark for credit unions and what drives their strengths.”

Almost three-quarters of all credit unions offer free checking compared with about one-third of banks and they typically offer lower interest rates on loans and revolving credit, according to the ACSI. These were major reasons that customer satisfaction with credit unions climbed 3.7% to an ACSI benchmark of 85, a good deal higher than for banks, large (73) and small (83).

Even as bank fees continued to rise and credit unions also began to use more fees, customer satisfaction with both financial institutions was still on the upswing, the ACSI found. Bank fees increased 2%-3% over the past year, which was the 15th straight year of such increases, but no negative repercussions have been detected regarding customer satisfaction. In part, this is because a fair number of consumers apparently have learned how to avoid the fees by exclusively using their own bank's ATMs and maintaining sufficiently large account balances.

“(Consumers) make a plan to get money out of their bank's ATM or they're going online to check balances,” VanAmburg said. ”There's been a lot of behavior modification, if you will, so that people don't end up paying fees.”

While the ACSI rankings trumpet traditional successes, resting on national results could backfire, said Denny Graham, president/CEO of FI Strategies, a St. Louis-based strategic planning firm.

“This is great news for the industry, but like politics, all member satisfaction is local. Every credit union with whom I've worked just knows they give the best service. Unfortunately, that isn't always true,” Graham said.

He advised credit unions to look to their own set of competitors, some of whom are pretty good at what they do, he noted. Graham recalled a conversation with a client who based their whole proposition on service and felt proud of their member satisfaction rating of 9.4 on a certain scale.

“Unfortunately, the same survey told them that though their huge bank competitor only rated 7.4, their local community banks rated equal to or ahead of them in most factors, as did some competitors,” Graham said.

Members also touted the wide variety of financial services offered and that accounts were easy to manage and understand, according to the ACSI. Credit unions also do a good job at providing multi-channel services, with members giving high marks to both websites and call centers.

“Credit unions are very good at multi-channeling. It's helpful to smaller organizations to maintain a good website and contact number,” VanAmburg said. “I know that it would've been nice to ask credit unions a decade ago (about their websites). As a credit union member myself, my gut tells me their websites may not have scored as well.”

The ACSI also found that unlike bank customers, members believe their current credit union offers competitive interest rates.

Still, members cited lack of convenient ATMs and branches as the most troublesome aspect of their service experience at credit unions, according to the ACSI. The report noted that banding together with joint ATM network access is one way that credit unions have been able to fill this void.

However, “the combo of the upside of the competitive rates and costs, the tendency to have fewer fees and better rates when borrowing money, customer service and community focus, outweighed this other issue,” VanAmburg said.

Credit union membership has swelled in recent years, hitting a record high in 2011, breaking it again a year later and on target for another record in 2013.

“Data from ACSI helps support what we have known all along – credit unions are here for the members who expect and deserve service, solutions, and satisfaction,” said Patty Veal, director of public relations as the $1.2 billion Pen Air Federal Credit Union in Pensacola, Fla. Meanwhile, overall customer satisfaction with retail banking is back to its pre-recession level, the ACSI found. Despite rising bank fees, customer satisfaction for banks grew by 1.3% over the past year to an ACSI benchmark of 78, which was up one point from 2012's mark.

JPMorgan Chase maintained the lead with a 3% gain to 76, while Citigroup jumped 6% to 74, and Wells Fargo edged up 1% to 72. While Bank of America registered its largest improvement in a decade, it remained in last place, and is the only bank that hasn't restored its pre-recession customer satisfaction levels.

“Even though banks have raised fees again, the 15th straight year of such increases, no negative repercussions have been detected regarding customer satisfaction,” said Claes Fornell, ACSI founder and chairman.