Definitely one from a manager. The second can be from a manager, professor, co-worker, or client, as appropriate. A few rules of thumb: 1) Make sure your recommendation will be positive--don't accept one from someone hesitant. 2) Make sure your recommendation will be personal--don't accept a generic, non-specific recommendation from someone distant or busy. 3) Don't look for a recommendation from someone with a conflict of interests, such as a family member or an employee.
Hope this helps!