With about 7,000 banks in the U.S., investors can't just buy any one. Some of the big and midsize banks offer the best opportunities, said Oja, and while each institution will give investors something different, investors should always be keeping growth in mind.
One of the banks that Oja recommends is JPMorgan, which has grown its revenues by 77 percent between 2008 and 2013. Its return on capital is "strong"; it's been able to add a lot of money to its capital ratios over the last four years, and it's growing globally.
The smaller, SunTrust Banks is also on Oja's buy list. It's seeing good growth in the Southeast, it's improving its commercial loan growth numbers, and it should be one of the big beneficiaries of the continued U.S. recovery, he said, adding that it's trading at about 12 times earnings, but that multiple will certainly grow.
While Liss has a more neutral opinion on the banking sector overall, he does like high-quality banks, such as JPMorgan, Wells Fargo and PNC Financial Services Group. He's also interested in banks that are growing through acquisition, such as M&T Bank, which is in the midst of buying Hudson City Bancorp.
Read MoreBank stocks to double, says Dick Bove
Also look at companies with a management team that has been through the recession, as they should know what to do if another crisis hits, said Oja. Banks that didn't have any losses in 2008 —PNC and U.S. Bancorp, for instance—are also good bets.
Overall, the sector does seem to be looking up. Expect revenues from the mid-sized banks to grow by at least 10 percent annually, while dividends and share buybacks should help push the prices of the big banks higher, said Oja.
"It's a different world than it was in 2006, but our outlook on the banks is still positive," he said. "People should certainly look at this sector."