If nothing has changed, I believe your options are either Walter Sickert, Finsbury, Heyworth, Peartree Court (the latter three being grouped together under the name and place of Finsbury Residences).
Walter Sickert - Very nice quality rooms, the only en-suite halls, very stringent rules and regimes, consequently very dead in terms of social aspects in relation to Finsbury Residences.
Finsbury Residences- It's arguable as to which is worst but I believe it's fair to say both Heyworth and Finsbury are at the bottom of your four options in terms of room quality. You'll have to share bathrooms and toilets with x amount of people (I think 4-6) but you do get a sink in your room. Since they are both practically under one roof (finsbury residences), the social aspect is pretty much identical, it's far livelier as opposed to Walter Sickert due to a far more lenient culture once you've entered into the structure.
Peartree Court - These are blocks of four bedroom flats with two toilets and a kitchen so you only share your bathroom and toilet with one other person. You do not get a sink in your room however the room quality is, on average, better than the other two halls in finsbury residences. Same as above on the social aspect. One important difference is that you DON'T get cleaners in here as opposed to Heyworth/Finsbury so depending on your flatmates, it could all go downhill very fast and you could end up swimming in excrement a couple of months into your residency. (Only really seen a couple of occasions when this has happened though and once you notify the staff, they will charge the guilty parties and clean the place up
)
In the end, it comes down to your priorities, if you can't handle the thought of sharing bathrooms and toilets and not having the nicest of rooms, go Walter Sickert. If you're some party animal and expect to have raves in your halls or even come home drunken and not have to tip-toe your way around choose one of the other three. Don't be too off put by the social downside of Walter Sickert though, I know people who are still having a good time there AND living like the proverbial kings. I'm very happy with living in Peartree and wouldn't change to anywhere else but I'm sure most people are the same wherever they're at.
Also, the Cass building is 10-15 minutes walk from the main campus and about 10 mins from halls. As a first year, you'll be required to go there about three times in the year, any other excursions to that utopia will be of your own choice.