Have halved our food bill I'd say through shopping at both Lidl and Aldi .I too have easy access to both and shop in both-like some stuff from Lidl better than Aldi and vice versa.For example:
Lidl better for loo rolls,kitchen paper,washing liquid,dishwasher tabs,beer,wine,sanitary products,jars curry sauce/pasta sauce,teabags,coffee,
Aldi better for face creams(brilliant),lipsticks,shower creme(like Dove),cold meats,cheeses,yoghurts,meat/chicken,dog food,bread,cakes,biscuits,
Both equally good for frozen veg,fresh veg/fruit,milk,eggs,sugar,butter,veg.oil,shampoo/conditioner,baking products,crackers,frozen icecreams/icelollies,chips,wedges,waffles,condiments,mayonnaise,salad dressings
This is from my experience in our local branches-may not be the same everywhere.