As stated in most of the threads, I guess it depends on what size bag you're looking for? Also the gm is a lot heavier then the pm and if you're looking for a shoulder bag, then the gm.
I'm sure you'll find more information then you need flipping through those threads. Good luck with your choice.
Crappy,
if you go up to the to and search manhattan, and tread title only it will give you a a list about 4 pages. you will see several of the ones listed there.