I would like to shop in Grand Frais, but am not prepared to drive 40km to the nearest one.
My nearest supermarket (5km) is Atac, and it's OK for anything prepacked. I wouldn't buy fresh fish or meat there though.
Lidl is improving, but nowhere near as good as in the UK. Aldi is a dead loss as far as I'm concerned.
Carrefour is to be avoided except for things I can't find anywhere else - it's expensive and I object to their attitude that if it's on the shelf they've got it, otherwise they don't stock it - they refuse to accept that they're ever out of stock of anything. Ed was Carrefour's cheaper end of the range and has now been rebranded Dia and in my opinion has gone even further downmarket.
Leclerc is improving - it was awful years ago, except in its original location of Brittany.
Intermarché used to be a franchise, so varied enormously from one to the next.
I'd love the quality of Waitrose, but would go bankrupt, so I stock up on the rare occasions when I go back to the UK.
After 26 years here I've learned to live with the limitations, but really miss the range and quality of basic cook's ingredients. Why is icing sugar so expensive here? Decent light brown sugar is unobtainable, as is cream of tartar (for home-made baking powder), quality dried yeast, and so on. I'm hopefully heading to the UK later this month, so will stock up on all of this, plus cans of Canada Dry, a bottle of sherry, and so on.