UAI cutoffs are basically determined on a case of supply and demand and may not be a true reflection of how good a course may be. I remember reading an article on NSW uni's a few years ago and UWS has the largest student numbers by a large margin, so it is fair to say more places offered = more demand satisified and UAI cutoff is lowered as a result.
Personally I have had a good experience at UWS. I've compared unit outlines of subjects to my friends studying psych at UNSW and Mac and we've all covered similar topics. First year psychology students participate in research (usually for honours students) as a part of their course mark, which helps to give an insight in practical experience and there are employment opportunities as a undergraduate research assistant (though this is competitive to get into). My friend is a psychology honours student at UWS and is enjoying his project a lot, he completed his undergraduate through UWS and also had a good experience.
There are many older threads comparing psychology courses at NSW uni's, you should do a search on this forum and have a look because there's heaps of info from different sources in them. I'm sure you'll also go along to the open days for each uni you're considering to attend, the people there are very helpful.
Hope that helps.