That's a strange question. If you are the speaker to state the fact, of course you would know which one suites the situation. Why don't you?
And shangban does not mean the person has a good profession. The person may either go to a good office, or a poor factory for a pity physical work (that's why I wrote "working place"). Shangban means the daily routine for one to go to the place regularly (usually weekdays. It's his job and duty).
Bosses, successful people, famous people usually do not need to go to their office everyday (shangban), so shangban really doesn't mean any good profession.
gongzuo is a formal word, even more formal than shangban. It is the equivalent of "work". One can shangban (go to his office) but buzhuanxin gongzuo (does not focus on his work). A man focusing on his "work" doesn't need to be in a specific place.