I think many would recommend multiple smaller ponds over one larger one. This allows different species in each, a variety of goals, and also an easier less costly path for maintenance. Think of the cost of treating a pond for an undesired plant in a 1 acre pond vs. a 3 acre pond.
When I first started down this path of having a pond built, I would have gone for the one large pond. But now, I would absolutely have multiple small ponds. If on the same level, you can always connect them later.
