Aldi for a big shop which is in the next town over (although they're jut finishing building an aldi about a mile from our street right now) and then morrisons in our town for in between shops. Asda for clothes sometimes.
Like some previous posters I'm rally disappointed with what I get for my money in most of the "big" supermarket. For instance last night I went to aldi and got a full trolley of food, drinks and cleaning products for £31 all much better quality than in the big supermarkets too I find.
Before we started shopping in aldi regularly I'd hazard a guess that we spent in the region of about £400 -500 a month on food, drinks, toiletries and cleaning products for the two of us, whereas in this last month we've spent £200 on food, drinks, toiletries and cleaning products. It's a win win really!