My cats like to travel - they're used to it, having done plenty of.
I have a clamshell front opening Avior (think bow doors of a car ferry), easy to get a cat in and out of, with lugs to take car seat belts. Unfortunately they're no longer made which is a shame.
I also have a top-loading rectangular wire carrier, which also a doddle to get even a very cranky cat in and out of. The lid locks with a separate retaining skewer.
The worst possible carriers are the front loading plastic jobbies with the tiddly gate door. They're not great to get cats in and out of, and the doors are flimsy, which can lead to escapees.
I have seen backpack cat carriers but I'm not sure I'd want to try either of mine with one...
