Is there a brand that you enjoy more because of the personal attention they've given you? Most often this is in the service industry, but it doesn't necessarily have to be that way. Sometimes it's because you had a problem with a product and they handled it so well that you immediately became an Advocate. http://www.youtube.com/watch?v=jk3vHSfWRuw
Ted Rubin, a consultant with Zuberance, loves Virgin America, Dell, BlackBerry, and Verizon. They won him over because he just loves brands that do excellent customer service. When they handle his problems well, he appreciates it, and he tells people about it. (Read Ted's recent blog post that highlights the importance of customer service here.)
The brands that get the most advocacy from Rubin are the ones who engage and interact with him on Twitter.