I haven't stayed at WL, but I can say a lot probably depends on your travel plans. Do you plan to spend most time at WDW or Epcot or even split park time evenly? Are you traveling with kids, and if so, what ages? Is pool time a big thing for you? Access to lots of restaurants? Etc. And then, sometimes, when everything is 'even,' it just depends on which hotel's theme you like best.
BC is a great resort, and people love WL. I don't think you can go wrong with either.