Tough choice. I have 2 shoulder bags (plum suede and whiskey) and a medium parchment Carly and I love them all for different reasons. I'm not into black bags lately (went through a period of time in my 20s when EVERYTHING I wore was black. Ok, now I sound old), so I'd vote for the parchment since I love the contrast of the deep mahogoney with the ivory and I love the hardware. But I'm biased by color and to be honest, I think the shoulder bag is perhaps my all-time favorite style.
Wow - looking at what I just read, I'm sure i didn't help you at all! I'm sorry, you just gave us a very hard choice!