I think the monorail to Epcot is your best option.
I figure the walk to MK would take the same amount of time as the monorail to the TTC. The boat from DHS would take longer.
And the walk from Boardwalk or Beach Club would take as long as walking from the front of Epcot.
So, the question is, which is quicker, a bus to one of those resorts, or the monorail? I vote monorail.