Hi,
Sorry that I can't help you with a BA recommendation.
However, can give my opinions on the areas which I believe will perform the best.
My first pick would be the geographic centre of Sutherland - Miranda.
It has a train station, multiple bus terminals, a multitude of medical services with 2 more complexes to be finished soon, not to mention Sutherland hospital also located in Miranda.
Then there is Miranda Westfields which is currently undergoing a $435 million upgrade/expansion which solidifies the suburb as Sydney's southern central business district.
http://corporate.westfield.com/video/?video=miranda-3
Miranda would be my first pick, followed by, (in no particular order):
Caringbah
Gymea
Kirrawee
The type of property you select and it's proximity to services will make a big difference toy your rental success in the long term, growth for all these areas I'd expect would be similar.
We have a 3 bedroom duplex unit in Miranda, about 200m perpendicular to the train station, so far enough for no noise, and it's never been vacant in the few years we've had it and getting $650/week rent. Just on the market now and 10 applications for it on the first open for inspection.
I'm not so up to date on the status of the market, but expect it's pretty hot right now.
It will be tough finding a great deal here, I'd expect the same in most areas of Sydney in this median price range where all the competition is.
Good Luck.