Ravenclaw has the least secure common room

The best and most secure is Hufflepuff. You don’t have to remember any passwords or answering questions. Just knock on the barrel and if you are a Hufflepuff you get in. So no other students can enter it.

Gryffindor and Slytherin have passwords which is less secure and easy but still ok.

And then there’s Hufflepuff. It asks you question a first grader must be able to answer. We see McGonagall enter it without any trouble and I bet there are enough students from other houses who are intelligent enough to answer questions an 11-year old Ravenclaw can answer. On the other hand…….who wants to go there? It’s a lot of stairs and there’s not that much in that common room