I think East Park is going to be in demand because it looks really nice and new. If you've been down there though, there's no bad accomodation and even the "old" halls are very new by the standards of many unis. Like Lafrowda is newer than almost anything at a lot of comparable unis. I'd say decide the kind of room you want first, (en-suite or shared, catered or non) and then put down that kind of room in the halls you would like. So let's say I want an ensuite, self-catered. I'd put down en-suite for HH, East Park and Birks and what I get, I get. I don't think there's much stock in trying to get a hall that's super close to your department or super close to the sports pitches - I just don't think that's going to change anything, and once you're there the differences between the quality of the halls will either be marginal or something that you couldn't have predicted unless you have a friend from the years above who can give you specific information.
So if someone you know tells you "don't pick x halls, the plumbing is really bad or don't pick y, it's really noisy from the building site next door" then that's a good reason. What I wouldn't do is buy into all this "Lafrowda is the party hall" thing. That is something that can change year to year depending on who shows up. Sure, HH might have more rahs. But that's a function of the fees. Also, just because the girl from the year above you at school went to Moberly and had a miserable time because she hated her flat mates - that has no bearing on you - because if you pick Moberly, you won't have those flat mates. The only time that's a thing is if there are halls known for Postgrads or International students - basically anything with a lot of studios or cottages. That's the only time you might be walking into something un-fun.
And by the way - no matter where you choose, for some reason you always end up walking up a hill.