OP: I think a lot depends on who you're going with (alone? spouse? boy/girlfriend? kids?), where you expect to spend most of your time, and if you intend to use Disney transportation or your own car. If Epcot and the Studios are a high priority, then you'd probably prefer staying at an Epcot resort. I'm not a fan of the Swan. I stayed there once--years ago, so the room interiors have changed since then--and I felt like I was at a convention hotel in the middle of Anywhere, USA. People seem to like that, though, so perhaps you would. There are a lot of businesspeople who stay at the Swan for conventions, etc., so one sees many people in suits around the hotel. I would not call it a luxury hotel. It's not a downscale hotel, but it's not the Four Seasons, which other people on the thread have suggested, and it's something you might want to consider.
If you're going to be at the Magic Kingdom a lot, the convenience of the monorail resorts can't be beat. You can walk to MK from the Contemporary--which is upscale--and take the monorail or a boat from the Poly and GF. I find the GF to be more luxurious than the Poly, but I'm not in love with the current style of the rooms there. The restaurants and lobby and shops at the GF are pretty darn upscale. If you like that sort of thing. But maybe Victoriana isn't your sort of thing.
When you have the chance, leave a little more info about your traveling party and access to transportation and you'll get more relevant responses. Because if you're going with younger children who are going to want to spend all their time in MK, then no matter how nice the Swan may seem to you, you'd probably much prefer staying on the monorail line, if not at the Poly, then at another monorail resort.
If what you're after is luxury and you have a car, then consider staying offsite. There are several very upscale hotels not that far from WDW.