In recent weeks the two biggest supermarkets have tussled over each other's advertising claims to offer the lowest prices.
In mid-September the Advertising Standards Authority upheld a complaint by Asda about a Tesco ad claiming it was cheaper, then the following week the ASA upheld a complaint by Tesco about Asda's claim of "lower prices on everything you buy, week in week out".
In the same month Waitrose used Tesco as its benchmark of value when it advertised a new pledge to price match Britain's biggest supermarket on 1,000 branded products.
But in our interviews the majority of people believed Asda was the cheapest.
Luke, a 22 year-old designer, said: "Asda, definitely Asda, they've got that new advert where you can check your code online and see how much you can save compared to other supermarkets. It's all over the TV, it's all over the radio, how they've got their price check."
Denise, a 56 year-old sales manager, said: "I would say probably Asda. You're always going on these price comparison things but I shop mainly at Sainsbury's, Asda's, Tesco's. It's swings and roundabouts. Some products are dearer, some products are lower."
Asda's advertising was a factor in people opinions, with Lynn, a 50-year-old social strategist, saying: "I would imagine Asda, because they are noted for being cheaper and more money saving. Their adverts denote that and promote that and my own experience tells me that they are generally cheaper."