If you have the opportunity, you should come down during orientation week and have a tour of each of the halls

I think that in terms of atmosphere, Carrington would be the most study orientated which a huge proportion of their students doing health sci and Cumberland probably the least. However at Cumberland they put you on a floor with students studying the same thing as you, so I think it would vary largely by what floor you are on... I was at Knox this year - it is privately owned by the Presbyterian Church and our Master is a minister of the church, but it isn't really religious apart from in a traditional sense. There is a Chapel you can attend on Sunday if you wish. I wrote that I was an atheist on my application and they still accepted me so don't have to be Christian or anything lol. Knox is really cool, has a good extracurricular and drinking culture but still is academically focused. There is definitely a sense of community. It is quite different to the other halls with second year students and many traditions. You should definitely come and suss them out for yourself
Carrington is a hall that will only accept you if it is your first choice (they will stress that when you go to look at it). Knox you can probably get away with as a second choice. And I think Cumberland is quite often used as a backup second/third choice.