Rowancroft accomodations (court/mews) are both nearer to St Luke's campus. So i'd avoid them if you can, mainly going to be medical students living there and you'll be far from Streatham campus.
Birks Grange and St David's are in the north west of campus....as town is to the south east of campus, you are about as far away from town as you can get in terms of uni accomodation if you live here. With Birks, you also have the infamous "Cardiac hill" to climb every day....which if im honest, i thought would be worse. I'd have climbed that every day relatively happily, great way to justify all that food i ate....
Anyway....I stayed in lafrowda when I was at Exeter, and i thought the location was pretty great tbh. it was on the south east tip of campus-the closest part of campus to town, but still not miles from the library and most teaching buildings, which are largely clustered around the center of campus.
James Owen Court is based in the centre of town itself. Its right next to the Odeon cinema (if that helps with Google maps....), pretty close to many of the shops you would want i guess...
Hope this helps. I can't remember much about the other's and their relative positions across the city/campus.