I also want a piece from the denim collection! But as for GM or PM, it depends on what you carry. Pm if you have less stuff and GM for if you have more.
If you get the GM you could use the front pocket to put your wallet and use the big pocket to put your sweater or whatever, something that you wouldn't need quickly, cause that space is deep. You should try it out, see which one you'd like better, which one looks good on you etc. and then decide on color, do you want a blue (which will always be around) or one of the limted eds?
good luck!