On a worker time basis for supplies, the Rio mission is by far the best, and Kiel second. If you cycle around every mission, you get 85 supplies at level 9 costing 12 worker hours or less, and 164 from level 7 costing 130+ worker hours. So 10 times the investment for about double the supplies. If you have any other uses for workers, having a level 9 dock and sending one worker on an expedition for supplies every day or so is likely a better bet.
Given that expeditions cycle through pretty evenly (never the same ones back to back, frequency of each seems to be the same), that does limit you to about 170 guaranteed supplies a week if you do all the level 9 expeditions that give supplies. Sadly low, compared to the other resources you can get for the museum. But at least the worker cost is somewhat reasonable.