The OP assumes that readers have a favourite, hence the question: “what your favourite”
Why would the OP assume that non-Lubavitchers have any favourite Chabad nigun?!
Wouldn’t the better question be: “Do you like any Chabad nigumim, and if, so what is your favourite”?
“Why would the OP assume that non-Lubavitchers have any favourite Chabad nigun?!”
Whether they know it or not, there are Chabad niggunim which have been accepted and spread throughout the entire Jewish world. If someone knows only one of them, it would by default be their most favorite.