The plastic coated top opening pens are good. The large ones. The cat can see out which mine prefer. Although some cats like to feel more secure in which case just pop a blanket over it. I like it as the sides are soft. On some of the plastic carriers my kitten puts his nose through the bars and it cuts him, not good when you're on the way to a show! The plastic coated ones are tough and easy to clean. What breed of cat will be travelling inside?