Our existing heater is on borrowed time and needs replacement before we have a catastrophe. Its in its own closet in the laundry room and there's no floor drain or drain to the outside. It is close to an outside door for flushing w/hose but there's no place for water to go if a serious leak develops. Do I really need to be concerned about the lack of a drain?

Is there a website with good unit comparisons to help me choose the replacement with best efficiency and features? Is there really any difference between brands? We'd like the new one to vent through a PVC pipe; we don't like the hot galvanized flue passing through the roof. There's only two of us so a typical 40-gal tank is adequate.