I won't scrimp on;
Make up - I buy No 7 which is cheap to some but I like it, I wait for the £5 off vouchers boots usually have on. I have Mac make up for 'going-out' as it's too heavy for day to day
Meat - hence we hardly buy it
Shoes - Kids always have 1 pair of decent fitting, leather shoes, I usually buy from Clarks and DH Skechers.
Bras - My GG monsters have to have decent support!
Coffee - DH moans if I get cheapo make
Beans - DH won't eat anything other than heinz or branston - says the other give worse wind than normal (suspect that may be a slight exaggeration on DH part)
Bread - I try to get decent bread as cheap as poss (can usually get kingsmill on 2 for 1.70)
Strawberry bloody milkshake - According to DH it has to be nesquik, everything else is vile
Peanut butter - Whole earth stuff for DH
Clothes for kids - Now I've started buying Boden I'm struggling to force myself to buy anything else (I do buy in the sale/% discount offers)
Mattress/Bed
Flooring/Laminate - Cheaper is false economy IME
Couldn't give a stuff about
Loo roll - actually prefer asda/tesco's own brand and we go through pack of 12 every week and a half, for 1.30 that is fab value
Tinned tomatoes - smart price all the way
Pasta - all tastes the same
Clothes for me - I look shit in everything so what's the difference 
Furniture - Will buy Ikea stuff, found it to last well and price is agreeable, although since sitting on my sister's cheapy corner sofa she got from tesco I will always get a decent sofa (new or second hand, don't care, in fact never had a brand new sofa in the 10y I've been with DH).
TV - Always had second hand, not fussed about flat screen etc.