More pros and cons here (specifically there are some of Tocil and Rootes).
Rootes in first place should have a very high success rate. There are some cases times where you won't get them (I'm not exactly sure why, perhaps because they ticked 'quiet area'?).
I must point out here that Rootes is very long (see this map
). Note that Rootes stretches along C6 and D6 - if you end up in Old Rootes you will probably be as far away from Maths as Cryfield and Heronbank. If you end up in New Rootes, however, you will be the same distance (roughly) as Whitefields and Jack Martin. Sadly, you can't choose between the blocks.
Obviously Tocil is the most ideally located block this year if you study Maths. You're pretty much close to everything else as well (I'd say anything like Whitefields and JM1 are the best located blocks in general when considering all lecture rooms/study areas).
OK, now Cryfield and Whitefields:
The sharing situation is roughly the same (about 6 to a bathroom and 12 to a kitchen). From what I have seen, kitchens in Cryfield are larger, but Whitefields has a lounge in each flat.
For you, Whitefields is in a better location.
Cryfield is corridor, Whitefields is flats. The Whitefields flats are completely isolated, meaning that the 17 Whitefields flats each are in a separate building and have their own front door that can only be opened by the 12 residents who have a key. Conversely, there are three Cryfield blocks with about 80-90 in each block. Front door of each block has a lock which can only be opened by the 80 residents living inside. Once inside, you can access any corridor in the building, each room has a lock which you can leave unlocked, allowing people to pop in and say hello.
I would personally choose Cryfield over Whitefields because I believe that the social situation is in general better in Cryfield (due to the flats/corridor).
5th choice can be: Westwood, one of AV/JM/Benes, one of HB/LS