As I see it, brand loyalty is not "this is the best, so I will buy it." Brand loyalty is, "this may not be the best, but it is made by the brand that I know, trust, and love, so I will buy it."
I thought this was the common perception of what "brand loyalty" meant, but apparently, between marketers, psychologists, and sociologists (all bullshit) they come up with horseshit phrases like "[brand loyalty] is determined by several distinct psychological processes and it entails multivariate measurements."
If you buy something because it is the cheapest, then I don't think you are brand loyal.
If you buy something because it is the most trendy, then I don't think you are brand loyal.
If you buy something because it is the most durable, then I don't think you are brand loyal.
Merriam-Webster
Loyalty
loy·al adjective \ˈlȯi(-ə)l\
1. Unswerving in allegiance
I think that to be loyal to a brand, or to possess "brand loyalty," you have to purchase the brand even if it isn't in your best interests as a consumer.
if we're using this definition, i think the only two brands i'm really loyal to are bank of america (i know, i know. but my dad spent nearly his entire career there. i can't switch banks) and texas pete (honestly prefer the taste of other brands better, but i like to support local companies)