Captains who are incapable of incorporating CRM into the operation. When I've got over 7000 hours of 121 flying, been at the company more than 5 years, with over 2000 hours on type, and the CA still micromanages everything about my involvment in the operation, they're going on the list. I don't have the patience to be paired up with people like that, let some junior pilot have that trip.