Journalists owe loyalty to the public. These are the people that they represent. These are the people that they serve. Hopefully they represent the people in an open, truthful and fair manner. If they don't....then the public won't buy the newspaper and that journalist might be out of a job. Their credibility and their reputatation might be shot as well.
Public Relations practitioners owe loyalty to their bosses and the companies that they have contracted to represent. Once again, they should represent their clients fairly and accurately. Earning a buck is important, but if a product, for example, is all hyped up...it should be deserving of all the claims that the PR rep is assigning it.
Loyalty would rank highly in a professional settting. I would need to be loyal to myself. Not in a self-serving way, like getting the story at all cost without regard for anyone or anything. Let me rephrase. I would need to be loyal to a set of personal and professional values that would guide my decision-making in an effective way.