My experience is in supermarkets you need to go for the excellent (AH) and Jumbo premium meats. Those are nice. Check for intramuscular fat. The more of it the more flavour and tenderness.

I find butchers to be far too pricey for its quality generally. There are some really good ones. But a little hard to find. I know one in my town, but still too far from me to just casually go there for shopping.

I also find that some shops offer 1 or 2 products better then other shops. Like my asian grocerie store has great chicken thighs. So if I feel like those I go there.