I am not a big in-park breakfast eater, but Sleepy Hollow would indeed be one of the better QS options in MK (not just at Breakfast time). At Epcot, if you are heading back to Ratatouille early, the Creperie has a walk-up window - the crepes there are pretty good! If you're staying more toward the front, I'd probably say Sunshine Seasons. Connections has more options, but it's also the Starbucks so it might be very busy early in the day. You can always grab a big donut from a Jofferey's kiosk too.