I shop where ever it is easy to shop. My fellow shoppers have little bearing on the experience.
Waitrose i claim 15% partner discount so i instantly have good reason to shop there, i like the beer/wine range and fresh stuff tends to be brill.
Tesco, big/ or small convenience locally, and coop in my village.
As for only choosing a market because it fits in with the badge on the bonnet of car you drive etc. tosh.