i like the fact fish are much more comfortable in a large pond with a great footprint, so i wouldn't care about the ability to veiw them as much, i wish i had more room to put large ponds though.
I can see having a pond inside or outside and placing fish in there to highten their colors and then bringing them inside for the winter placing them into required sized tanks.
Aquarium because of the side view, but as someone mentioned and an idea came up build a pond indoors to keep it much cleaner and build a pit next to it with stairs and a window so you can also have some side view.