Love them both, use the Nightingale more.
I travel a lot, and it's essential for me to have a bigger bag that can double as a carry-on (but still look nice when carried as a regular handbag). There isn't quite enough room for all of my travel necessities in the Pandora (I have two of the Medium size), and I really appreciate the extra height my Nightingales offer.
When I'm home, just running errands or out shopping on the weekend, I usually reach for my Pandoras. They are a bit lighter, and the cross-body option is awesome!