I prefer the eggplant one because it doesn't have the gold "pieces" (sorry I don't know the word in English) detailing above the zipper that the red one has. For me a zipper, doesn't go out of style, but the extra gold detailing might (it also looks less dressy to me, if you are planning to use it for dressier occasions too).
I can attest to the good quality of M&N bags. I've had my large black handbag for about three years now, I have worn it lots and lots and it still looks brand new.