Hey, I'm also from the US and recently applied for ESCP's MSc in Marketing & Digital Media and IE's MiM!
Being from outside of Europe, it's hard to really grasp the international scope/reputation of each of the schools, but from what I've gathered, ESCP does seem to be particularly strong in digital marketing (and their Marketing & Creativity program looks very unique, too). IE seems to have a pretty customizable MiM program, as well, so you could still specialize in digital marketing if that's the route you decided to take (which is also my plan if I go there). If you know for sure you want to go into marketing, the a specialized masters may be the way to go, otherwise an MiM program may be be more well rounded.
If you're currently working as a manager, will your company pay for your education? If so, why not consider an MBA program?