I use the rule of "second shittest" for thing like loo roll, squash, butter etc
This is a brilliant rule and great name! I agree with all three of those things. I'd add ketchup, because sainsburys/tesco basics ones are awful, but aldi/lidl 45p bottles are really nice! See also their lemonade - not sugar free, the normal one.
Most cheapest value dark chocolate can be really nice. As can milk and white, I use them for cooking with - just avoid sainsburys and lidl's white.
I'm lol at all the tinned tomato snobbery here 😂 I only use then for cooking into stews and not, say, as an accompaniment to a full English like some weirdos. I have tried expensive ones and really don't notice a difference in a casserole or stew, no. I add a pinch of sugar to anything tomatoey, it makes a big difference. If I want more tomatoey flavour I'll add tomato puree (39p aldi!). I generally prefer cooking with passata, which I do think the more expensive ones taste nicer but there's such a massive price difference and the more expensive ones often have extra unwanted ingredients to enhance their flavour anyway, that I tend to stick to cheap.
Sidenote but have you seen some of the ingredients in some tinned veg?!?!?! You'd think they'd just be in sugar or salt water, right? There are colourings and artificial preservatives and "flavour enhancers" in some - an innocent tin of peas, for instance! Sometimes I buy cheapest to avoid them, sometimes cheapest are the culprits! Take peas for example cheap lidl peas - full of colouring, branded mushy peas (batchelors I think) colouring and shit, value mushy peas just peas and salt!