If your building it, build in an overflow and go sump. You could build it to where, if needed, you could just open a valve to drain the tank.
Are you building out of plywood? Acrylic? Glass? Concrete?
What kind of turnover rate are you after?
Is the tank show or utility?
Are you building on the cheap or is money no object?
Is noise going to be a factor?
How many fish do you plan on stocking said tank with?
More info is needed to answer your question.