The banks that will win at customer retention and acquisition in the future will be those that have mastered the channel game, recognizing that new digital channels are complementary and not a replacement for older contact points.

Gina Sverdlov, a Forrester Research analyst and author of the new report, "What Drives Retention and Sales in U.S. Banking," suggests banks keep one foot firmly planted in both the future and the past, forging a cross-channel sales and service culture that can equally swing between mobile, web and more traditional venues such as phone calls.

Phones are not going away, and are still a primary means of connecting with banks, even for customers who are tech savvy. "There's been a lot of attention placed on mobile and online channels. While that's important, markets should not forget offline channels," Sverdlov says, adding that nearly a third of U.S. adults who are active online still use traditional channels such as phone calls when attempting to solve a service problem with their bank.

That's not to say that the investment in mobile apps has been in vain. It's necessary, but not at the expense of call centers or branches. "Almost 80 percent of U.S. adults are online daily, and half own a smartphone," says Sverdlov.

One of the major investments banks have made in the past year or so is in technology that allows CRM systems to link to digital channels, particularly mobile as smartphone banking increases. The goal is to allow a customer who engages the bank in different venues to hear and see the same information. Sverdlov says that innovation will need to continue as consumers use different venues, often at the same time, to engage with their bank. "People don't just engage on one channel, such as a phone or email, and when they make a phone call, or go online, they are going to have the same experience," she says.

Forrester based its findings on an online survey in June of 11,413 U.S. individuals aged 18 to 88. Among all factors that drive acquisition and retention, trustworthiness comes out on top, followed by low (or no) fees, customer service, good mobile and online banking service, and generous rewards. Lower on the scale are having many locations, offering a low annual percentage rate (APR) and a maintaining a variety of product offerings.

Among financial institutions, JPMorgan Chase (JPM), Well Fargo (WFC) and Bank of America (BAC) had the highest association of trustworthiness, low or no fees and good customer service, which suggests strength in customer acquisition. USAA, ING Direct (ING) and PNC (PNC) showed the highest retention potential. Forrester says that only 1% of USAA customers and 2 % of ING Direct customers were likely to switch providers, compared to Citigroup and Bank of America, where 12% and 11% of customers, respectively, were considered likely to switch financial service providers.

Citigroup and Bank of America have shown up in other recent "likely to switch" surveys. Both banks have said they are improving multi-channel outreach and social media to improve customer experience and to handle customer service queries faster.

USAA, an institution that focuses heavily on military personnel and their families, has embarked on a number of new channel initiatives, including video access to customer service from remote locations and low bandwidth web banking for military members that are stationed overseas. The institution is also developing voice recognition technology. Called Nina, the voice recognition is similar to Apple's Siri: users make a vocal request through the app, which is processed by Nuance. Nuance's natural language software processes the requests, then sends a response to the mobile application. Additionally, USAA is expanding its network of financial centers that include two-way video and other technology that connects the institution's members to customer service.

"We find the more [members] take advantage of these tools, the more they want to keep doing business with us," says Wayne Peacock, executive vice president of member experience at USAA.