The DIY chain scored just 55 percent for customer satisfaction. It bumped PC World, last year's most unpopular online store, from bottom place - but only just, with PC World still scoring just 56 percent. Third from bottom was WH Smith, with a score of 59 percent.
At the top of the list, for the fourth year in a row, was Liz Earle. The beauty retailer scored 95 percent for customer satisfaction - thanks largely to a policy of giving customers little freebies. "Items ordered always arrive promptly and individually wrapped, which makes you feel like you are receiving a present rather than a purchase," commented one survey respondent.
John Lewis - whose real-world shops regularly top customer satisfaction surveys - scored highly for its website too, with an 89 percent satisfaction rating. Meanwhile, new entrants Wex Photographic and Toolstation went straight into the top ten for their knowledgeable staff and efficient delivery policies. Amazon, the world's biggest internet retailer, slipped from third place to joint 11th with 84 percent.
But according to the Which? survey, delivery issues still tarnish the online shopping experience. The Royal Mail was popular, but courier services - and in particular City Link, with a 56 percent satisfaction rating - came in for most criticism. Customers reported issues with items arriving damaged, late - or not at all. Survey respondents also complained about being forced to pay too much for postage and packaging, as well as a lack of choice over delivery times.
"Online shopping has never been more popular with cash-strapped consumers looking for good value and customer service," says Which? executive director Richard Lloyd. "However, the industry falls down when it comes to the performance of its delivery partners."