Seems that the Coach is longer and shorter than the MK, which means that it will be easier to put your things and find them in the Coach. On the other hand, the Coach has an outside pocket that can be useful .
But keep the one you like best... Both are very nice.
Coach. The zippered pocket on the outside and the fact that it can be worn with a crossbody strap makes it more functional while its matte canvas is more subtle and trend-resistant. There's just something about that mirror canvas on the MK that makes it look plastic-y instead of luxurious.