Carrefour supermarkets are situated in Villaggio Mall and City Centre Malls in Doha. They are a French chain.
In Doha they are clean and serviceable and many people shop there. Best to try and avoid peak times.
Not my favourite supermarket but we go there to pick up odd things we cannot get elsewhere. I expect that you will end up doing this too, going round a few supermarkets to get all of the goods from home. Being English, I like to bring home comforts with me.
Carrefours also sell electrical goods, clothes and usuall have a small cafe area as well.
Try Carrefour and see what you think.
Also if you ever get to Calais in France, try the Carrefour Hypermarket there, that is well worth a visit.