i lived in heathfield when it was first built!...
from personal experience, i think heathfield is better than belmont. Cos in heathfield its more community based. Whereas belmont is divided into two parts, one for undergrads and the other side for post grads, and it just isnt as 'cosy' feel as Heathfield. In heathfield its more of a community.
Also, Westpark is a tricky one. I actually like westpark VILLAS [big room/double bed, and u share with many people, and theres a communal area, so its easy to make friends] but then the new westpark, is basically the exact same as belmont or heathfield..so i personally wouldnt live that far for the new built, but i would maybe for the villas. its a 20-25 min walk to uni and probably 30min to city centre. so its not THAT bad.
how come noone mention seabreas?...its also new and old build there. similar to westpark. i think i would choose seabraes over westpark though.
but yeh in heathfield i was in a mixed flat, and although it was great, it was just me and another girl. everyone else were in all girls or all boy flats, and they seemed to have a better 'clique', since usually it was a boys flat living across the hall, so itd be 'exciting'. but i loved my flat, but if i could choose again i would have opted for an only girls flat.
good luck!