I go for a balance of Price, Quality (not some sales hyped 'Quality or Luxury' version) and Selection.
Same product: Walmart's price will probably win if more than 2-4 percent lower.
Sears used to have (advertise) 3 qualities of some products. For most it was 'Better'. For Long run usage it was 'Best' (Like Craftsman hand tools)
Now days it is about Cheap or Luxury.
Cheap is still
cheap
Luxury is just
expensive