Shoppers vote with their feet and wallets as Aldi tops satisfaction survey
Aldi was placed first in the in-store category in the survey of 6,800 shoppers who were asked about their experience of shopping for groceries both in-store and at online supermarkets over the previous six months.
Despite Aldi's stores being described by some in the survey as "untidy" and "a jumble sale" and customers complaining about rushed checkouts, value for money was a key factor in its climb to the top spot.
Supermarkets were ranked in the in-store category based on consumers' feelings about the appearance of stores, queuing time, staff availability, the range and quality of products and value for money.
Waitrose, which had previously held the top position for three years, fell to fourth place.
Separate studies have previously suggested that the "Waitrose effect" of having one of its stores nearby can help to add value to residents' homes.
Which? said customers gave Waitrose a two star rating for its value for money, in contrast to Aldi's five.
Which? said Aldi's special offers rated well, as did the quality of its fresh and own-label products and the ease of finding items on its shelves. It is the second time Aldi has come top in Which?'s annual survey - the previous occasion was in 2014.
Matthew Barnes, chief executive, UK and Ireland at Aldi, said: "We're over the moon to be named the best supermarket in the Which? annual customer satisfaction survey voted for by UK shoppers.
"At Aldi, we're proud to offer fantastic quality products at amazing prices and to be named the UK's favourite supermarket shows just how much we are resonating with shoppers."
Aldi fans loved the supermarket's "fantastic prices" with many also praising an "always improving" selection of food, Which? found.
One customer said Waitrose is "a bit pricey - which is why I don't do my main shop there", while others praised its "top quality" produce and "polite customers".
A Waitrose spokesman pointed out that Which? had awarded its shops more categories with a five-star rating for customer satisfaction than any other retailer in the study and that its score for its online grocery service had also improved.
Five star ratings were not directly linked to Which?'s overall scores. The Waitrose spokesman said: "As Which? itself says, many customers praised our top quality produce."
A Sainsbury's spokeswoman said it was "confused by the methodology" used to create the rankings, pointing out that its stores had outperformed the top-ranked in-store supermarket in the star ratings system on measures such as store appearance, queuing time, staff availability and range of products and had matched it on quality of own-label products and fresh products.
Meanwhile, in the online category, people were asked about the convenience of delivery slots, the choice of substitute items and drivers' service as well as quality, product ranges and value for money.
Among the online supermarkets, Iceland claimed the top spot for the third year running, which it shares with Ocado for the first time.
Iceland managing director Nigel Broadhurst said: "We are naturally delighted to have been recognised once again as Britain's best online store in the annual Which? supermarket survey.
He continued: "We are also a business that is and has always been committed to doing the right thing, most recently reflected in our aim to eliminate plastic packaging from our own-label range by 2023.
"We look forward to welcoming many more new customers to enjoy the Iceland experience, both in-store and online, in the year ahead."
Iceland received five stars for its drivers' service and the availability of delivery slots - with three-quarters (76%) of shoppers saying their most recent order was delivered on time.
Asda was placed at the bottom of the online supermarkets table, where Which? said it has been for more than a decade.
Alex Neill, managing director of Which? home products and services, said: "With food costs rising it seems as though shoppers have felt the pinch and are voting with their feet and wallets.
"Aldi and Lidl have won over their customers with value for money, knocking Waitrose off the top spot."
Here are how the supermarkets were ranked by Which? in the in-store category:
2. Marks & Spencer
And here is how they were ranked by Which? in the online category:
5. Amazon Fresh