I'm guessing the key thing is to be yourself. Corny, yes. But I think its probably the best way to go about it. Especially because this is used to group people together. This is especially important in the larger halls and the self-catered halls. Be consoled by the following:
1. Almost all Bristol students come love to the hall they are allocated
2. You might think your choice of hall is the most important thing now, but in a few months it will be clear that the people you live with are what will really make your time at Bristol.
A lot of people I've spoken to have said to go for Stoke Bishop, and a lot have also said to go for Clifton halls- the difference is the halls these people are basing their experiences on. Even the houses might not look too appealing, but they aren't beyond liveable.
Personally, I really like the thought that when I get to Bristol in October (all things being well), I will be living near to students who someone with a wealth of experience has felt I would live near to. That, surely must be more important than our own hall (but it is obviously worth going for the best hall as well
).
Everyone needs to chill. Relax.