Both operators achieved a score of 50 per cent in the poll based on more than 4,000 customers’ experiences by the consumer group, Which?
Only one in five EE customers said they would definitely recommend the company to a friend or family member, despite its record of strong coverage and fast 4G download speeds, the watchdog said.
Just under a quarter said they would recommend Vodafone.
EE was fined £2.7m by Ofcom in January after the regulator found the company twice broke a “fundamental billing rule”, leaving nearly 40,000 customers overcharged by around £250,000.
In October last year, Ofcom fined Vodafone £4.6m after two investigations found the company was mishandling customer complaints and had failed to credit the accounts of more than 10,000 pay-as-you-go customers who topped up their accounts.
Both operators said they had committed to making improvements.
Giffgaff, owned by O2, and Utility Warehouse, which offers gas end electricity as well as phone and broadband, topped the Which? survey table with scores of 81% and 76% respectively.
Some 70 per cent of Giffgaff’s customers said they would recommend the network to others.
Plusnet Mobile, the recently-launched service from the Sheffield-based broadband supplier, was placed sixth in the satisfaction survey, which also found that a quarter of mobile customers had switched their provider in the last two years.
Last week, Ofcom announced plans for a “text-to-switch” scheme to allow customers to move to a new network within 24 hours and avoid the need to speak to the outgoing supplier.
Alex Neill, Which? managing director of home products and services, said: “Year after year we see the smaller providers giving great service and some of the biggest providers struggling to meet their customers’ expectations.
“Those who are fed up of receiving a poor service from their provider should look to switch.
“It is critical that the next government and Ofcom listen to the concerns of mobile phone customers so that there is increased competition in the industry which will lead to a better experience for customers.”
A Vodafone spokesman said: “Improving our service for our customers is our top priority. After a difficult year in 2016, many of the improvements we have made are becoming real to our customers. We are determined to become the UK’s best mobile service provider for customer service”
EE said: “Getting a good 4G connection is one of the most important factors for consumers, so it’s disappointing that these ratings don’t take network performance into account.
“Which?’s own report shows that EE customers get the fastest 4G connection in the UK, and are on 4G more of the time than any other network. “We’re continuing to work incredibly hard to provide the best mobile experience in the UK by rolling out 4G to more places in the UK than any other network and becoming the first operator to answer all customer service calls in the UK and Ireland.”
An earlier report, by the website uSwitch, rated Vodafone the third best network for customers on pay-as-you-go tariffs.