I have never had a Quaker, but the one that flies around my vet's office is pretty screechy. However, I don't think she is as loud as my conure is. It's a different pitch though, higher and maybe scratchier, if that makes sense.
It's not always so much the volume but how often they do it as well. My amazon can be my loudest bird, but he rarely screams. My conure is pretty vocal a lot of the time, but not necessarily loud all of the time.
It's definitely a good idea to spend time with one to know for sure if you can tolerate it, and whether you think your neighbors can. You can always talk to your neighbors first as well. They may not care. Mine say they can't hear my birds from inside their houses, although none are close either. They can hear them when they are outside, but say they don't mind at all.