EE has been named the UK's worst online shop in an annual ranking topped by electricals retailer AO.com and the beauty specialist Liz Earle.
AO and Liz Earle both won praise for their speed and efficiency and an overall score of 87% in the poll of more than 10,000 members of the public by Which?
Telecoms provider EE scored just 58% from consumers, who said its website was hard to navigate and lacked information.
Evans Cycles and Vodafone also performed poorly with a score of 59%, while Homebase managed 60%.
EE's poor showing follows it ranking towards the bottom of the consumer group's customer service survey last month.
Which? asked consumers to rate the online shopping sites they use across a number of sectors on factors such as price, deliveries, quality and ease of finding products.
The survey found that price is the most important consideration for shoppers deciding which website to use.
Which? editor Richard Headland said: "Online shopping is booming because it can be more convenient, better value and offers a greater choice of products.
"However there is a big difference between the brands at the top and the bottom of our table suggesting some sites need to be a lot more switched on to what their customers want."
Online shopping accounted for 7.3% of retail spending in the UK in 2009, rising to 13.1% last year, according to retail consultancy Conlumino, which forecasts the figure to reach 18.3% in 2019.
The top 11 online shops according to the Which? survey are:
1. AO.com (87%)
= LizEarle.com (87%)
3. ToolStation.com (85%)
4. JohnLewis.com (84%)
5. Wiggle.co.uk (83%)
= TheBodyShop.com (83%)
= AllBeauty.com (83%)
8. Ebuyer.com (82%)
= FragranceDirect.co.uk (82%)
= Amazon.co.uk (82%)
= MACCosmetics.co.uk (82%)
The bottom 11 are:
100. EE (58%)
98. Evans Cycles (59%)
= Vodafone (59%)
97. Homebase (60%)
96. PCWorld.co.uk (63%)
93. H&M (64%)
= Laura Ashley (64%)
= WHSmith.co.uk (64%)
90. Zavvi.com (65%)
= MamasandPapas.com (65%)
= O2.co.uk (65%)
:: Which? surveyed 10,505 members of the public in July.
An EE spokeswoman said: "We always aim to offer the best products and services for customers visiting our stores, calling in or shopping online, so we're disappointed by these results.
"We have a comprehensive programme in place to improve service, including our digital customer experience with new digital help sections and online account tools for our customers."