Rivals, especially Three, are catching up fast though.
EE has come out on top in a major performance test of the UK's mobile phone networks over the last six months.
The network scored highest in the six central categories of the Midyear UK RootScore Report from RootMetrics, with its customers reportedly enjoying better calling, texting and mobile internet performance than rival operators.
However, the network did not have it all its own way, with rivals Three and O2 making major strides from last year's performance, with Vodafone following in fourth place.
EE scored highest in terms of call quality and mobile internet performance, as well as the speed and reliability of its network, but RootMetrics said all four of the major networks showed a marked improvement over last year's results.
Three performed particularly well, taking top spot in Northern Ireland, and running EE close in several of the categories, winning or tying for first place in 25 metropolitan areas across the UK.
"Our mobile phones have become an essential part of our everyday lives, but determining which network performs best seems to have become more difficult," said RootMetrics CEO and President Bill Moore.
"We firmly believe consumers deserve clear, unbiased, and accurate information in order to make the most informed decisions to improve their everyday mobile experience."
EE, whose 4G network covers more than 73% of the UK population, said that the news was proof that its continued investment in improving its services was paying off, in spite of it being named the most complained-about mobile service in an Ofcom report earlier this year.
"Today's results, along with last week's report from Ofcom, show that EE is providing the best mobile experience to businesses and consumers across the UK," said Olaf Swantee, EE's chief executive.
"We continue to invest in getting even better, and setting new standards for performance and reliability."
To gather its results, RootMetrics conducted nearly a million samples across the UK, with its researchers driving over 25,000 miles to take results in both indoor and outdoor locations.