its not one or the the other though it is very possible to do all of them. build floating Venusian bubble cities, make O'Neill cylinders orbiting around every celestial body of note, while building tunnel cities on mars and the moon and hallow out asteroid and build Stanford Torus in them . We are planet of over 7 billion people we can do more than one thing, and the more varied and distant the baskets humanity is spread to the better.