Been shopping Aldi / Lidl since my student days, with the odd top up shop from Morrisons, ASDA and last resort, Tesco.
Tesco have always been poor for value, some real good bargains if you find it or glitch it (HUKD) but they're rare. Think the latest farce exposed them too much, even Warren Buffet sold his shares and admit he's made a mistake on investing in Tesco.
Oh dear.
e: I previously work for a food manufactuer that catered for Tesco's range of ambient cakes. All they're concerned about is, how can we get the same quality cakes as Sainsbury / M&S but at a cheaper price. Squeeze, squeeze, squeeze at the manufactuer end whilst keeping their profit margin up.
Aldi on the other hand works fairly. Negotiates better targets than squeezing the manufacturer to get value for customer.