I can’t think of one. Brand loyalty is typically not good for consumers. Preference is one thing. If you prefer their product, then you are getting more utility from buying it than you would a substitute. But being loyal to a brand implies that you would buy their product even if you thought it was inferior to its substitutes.
Maybe Sega when I was younger. I had the SNES and the Genesis. But then I got the Sega CD, the Saturn, and the Dreamcast even though most people I knew had a PlayStation. And I loved the games on the PlayStation. But I really wanted Sega to pull through for some reason.
Probably because, while the other systems had a lot of good games, the Sega systems would once in a while have an exclusive game that was really innovative and great. And I tend to want to play those games over and over rather than want to learn how to play a bunch of newer, slightly less quality games. I don’t know if that’s loyalty or preference.