The best for air travel
We are diplomats who travel with a full house of dogs and cats, changing posts every 2-4 years. After trying many brands and types of travel crates, we have settled on Kennel Gulliver: easy to assemble, sturdy, secure, open enough for air circulation, closed enough to allow the animals a sense of security. And it bears up well to the rough handling that baggage personnel can sometimes inflict.
My only suggestion for improvement would be that all sizes, not just the 70, come with the wonderful removable floor that separates the dog or cat from any urinary accidents. Until then, be sure to get puppy pads for the smaller siezes.