I prefer tubs to tanks. Tanks don't provide much airflow since they are generally taller than they are wide. Tubs have a lot of floorspace and allow airflow as long as it's in a well-ventilated area. Plus they are lighter, less expensive, easier to clean, the list goes on. If you construct a rack properly, rats should not be able to chew their way out. I haven't had a single escapee in two years.