If I had to choose, I'd say chem inhalers, as it helps you actually get into close combat (and stay more effective without hiding behind stuff).
However, I believe that the best way to handle morale when it comes to close combat is simply to win the combat every turn. Thus, I would be more inclined to bring a priest for a command squad, than give 4 units chem inhalers (assuming that you can play it so that the command squad will be able to support whoever is flagging).
Or, better yet, just keep your CC HQ with a standard at the point in your line that needs the most supporting. Not only will they be there to help you win combat, but they would also be able to help you by running in and scoring some kills.