Fantastic Fan was noted for many years for fantastic customer support. But they have new owners now and I do not know how the support is.
Maxx Air has a "Downdraft" fan. it blows down onto the roof. So what is the advatage. You can leave it open in a downpour and since it blows DOWN (not up) its rain proof. Where as the best fantastic fan will shut down and close if it detects rain. the Maxx Air simply does not care.