I'll pick the Congress every time. It is true that a president usually can get any one thing he wants through the Congress. But to do so he may have to give up fifty different things key members of the Congress demand. Despite the prestige of the White House, the presidency is clearly the junior partner to the Congress under our system. Therefore, if you are serious about governing, you must have power in the Congress.
Career opportunities abound there.
Staff as well as elected members have real power. Career bureaucrats have power as well. Conservative Republicans are rare as diamonds in the Foreign Service and the Civil Service. Yet there is no reason why we should grant the liberals any monopoly in these areas. The pay is good., and the job security is about perfect.