I virtually only buy own brand, and most often the Basics own brand at that. There are some that I've tried and found not to be so nice, but quite often the Basics stuff is only odd sized stuff that doesn't make it into the 'better' stream. And quite often the own brand stuff comes off the same production line as the branded. I remember when I worked at Iceland, 20 years ago, we were told that Nabisco make all Weetabix and wheat-bisks. (Although Sainsburys basics wheat-bisks are one thing where I found them to be lacking, so the supermarkets may now source the lowest price ones elsewhere)
I something wonder if the staff think I have some sort of OCD-autism about food, because I tend to buy Red Leicester cheese, and sometimes, if I've bought an orange pepper too, my entire shop is orange and white!