Go to your local butchers - it will always taste better than the value versions from a supermarket, and be cheaper than the normal supermarket price. I bought some Sainsbury's orange label (their own brand thing) lamb shanks for a casserole last week when the butchers was closed and nearly threw up it was so horrible - greasy with no flavour. I'm actually a good cook and can normally use herbs very well, so was shocked at how bad it tasted.
Aside from the meat, I always use Sainsbury's own: jellies, flour; pasta; butter (in this case not the orange one, and from a previous post of mine you'll see I make my own normally too!); veg is always bought loose. Cheese from their deli-counter.
I go to farmfoods for frozen brand name stuff and for their milk sometimes (£1 for 2L), crisps, biccies and sweets.