Your friends don't care what brands you like! I promise you.
I think it is possible for someone to desire their friends to know a thing about them even while knowing that their friends don't actually care about that detail.
Maybe a subtle unconscious change about how one is thought of might possibly be a result? (I don't know, but I don't think I can rule it out as a possibility that could be desirable to some.)
A few brands that I have very high affinity towards: Crumpler, Nike, and Canon.