I go to sussex uni and what I would say is that you shouldn't disregard somewhere because of the accommodation! I applied for the en-suite rooms such as Swanborough and Northfield and I ended up in Park Houses (which was my 8th choice out of 10!). When I arrived I was adamant to put my name on the swap list, but now I've lived in it for a few months I absolutely love where I live. I wouldn't swap for nicer accommodation now if you paid me.
Lots of my friends live in East Slope, and they were all apprehensive about living there but now it's grown on them so much they wouldn't move out. Ok, it's not ideal in terms of hygiene but you've got to remember that Swanborough can get dirty too if people don't clean it!
I've found that if you want 1st year to be a sociable year, it's better not to have ensuite because if you have one you don't really need to come out of your room.
Also you're only there for a year... the course/location is so much more important than what halls you could be living in!