Yep that's pretty much it, Epcot or Magic Kingdom. Both offer great views of their perspective park if you get the right room. We had a top floor room at Boardwalk and walked out on our balcony every morning to see the Eiffle tower and Spaceship Earth. The room we've had at Poly was simply wonderful since the refurb, but not as a great a view but did have some lovely tropical gardens right off our patio. Both resorts have great pluses. I would say Boardwalk skews a little more to the adult side and Poly skews a little more to the young kid side. Boardwalk has some excellent restaurants and entertainment with the ESPN club and Jellyrolls as well as the carnival atmoshpere on the boardwalk itself. Poly has arguable the best breakfast joint in the "World" with Kona Cafe and great fun and dining at Ohana and their Luau show.
If you are a big fan of Epcot, especially the World Showcase side, I would highly recommend Boardwalk. It's no more than a 5 minute walk from the lobby to the international gateway, Epcot's back door.
Now if you're a bigger fan or Future World fan or the Magic Kingdom, I'd lean towards Poly. The MK resort monorail stops right at your resort, so easy to walk on right on and ride over to MK. Depending on which Poly long house (building) you are staying in, the TTC is just next door. There you can catch the Epcot Monorail and ride a direct monorail right into the front entrance of Epcot.
You can't really go wrong with either.