The survey looked at banking services including budgeting tools, home loan applications, mortgage repayment calculators and email alerts.
Westpac's chief digital officer, Simon Pomeroy, said the bank's objective was to give its customers the ability to do most - if not all - of their banking online.
"More than half our customers are using online banking regularly and this number is rising every month.
"We're also finding that customers are using multiple devices throughout the day."
BNZ's award-winning YouMoney app got a special mention in the survey, for giving customers more control, insight and better decision-making when dealing with their money.
A spokeswoman said the app had been particularly popular with under-25s.
ASB - which reported it had had more than 100 million logins across its online channels - was leading the way with a function that allowed customers to make extra payments on their home or personal loan.
The function had been hugely popular, with up to 6000 extra payments made a month.
ASB's executive general manager of technology and innovation, Russell Jones, said that was one of a number of initiatives they were working on to improve the digital banking experience.
The bank's new Card Control function lets a customer restrict how and where a credit or debit card can be used - including putting a temporary block on it if need be.
Kiwibank's Home Hunter function had "re-invented home-buying" for New Zealanders, the survey said, by giving people access to the latest home listings and images.
SBS had put a focus on faster access for its customers, while HSBC had tapped into the international market introducing the Chinese currency renminbi (RMB) - allowing customers to transfer this to other international accounts.
ANZ found it had about 750,000 customers coming into a branch each year simply to change a pin number.
That led to a function on its app that allows customers to easily change pin numbers on any card whenever they like.
Read the full report here: