For me the main advantages are space, mess and noise. Tank upstairs is dead quiet, I'm yet to spill a single drop of water on the main floor, and underneath and around the tank doesn't resemble a nuclear reactor.
One of the main disadvantages of basement sumps is the extra head pressure so my setup is a little different from others to minimize this. The main pump sits in the top sump which feeds the display while a smaller pump circulates water from the base sump to the other three. The result is about 7 feet of vertical head on the main circulation pump and a combined wattage of less than 100W to pump over 1000GPH to the display.
I built my sump room into a pantry that I will likely convert into a wine cellar if/when we sell the house. It's not done yet, once I figure out all the equipment I want to run I'll rework the plumbing and electrical so it's more organized.
