Which park do you think you are going to spend the most time in? If MK, then WL would be the way to go. If Epcot and/or HS then BWI would be the way to go. Other than getting to MK, you are going to bus just about everywhere from WL. You could take the boat to CR then hop on the monorail to TTC then on to Epcot that way. If a BWI you are going to either walk or boat to Epcot and HS, you are going to bus to AK, if you have park hoppers it's possible to walk through Epcot and monorail to MK but frankly, it's just as easy to bus it.
What is your party make up? All adults, adults and kids? My son is grown now and we love the Epcot resorts, it's just so easy to hop over to Epcot just about every night to eat. I would think if you had little ones, WL might be the better bet because of proximity to MK.
If location, location, location doesn't matter, I'd probably just go with which ever one is less. Like I said, we love the Epcot area resorts and MK is just a half day park for us but WL is a beautiful resort.