I'd recommend Tokyo as there is a lot more to do there than any of the other Asian parks. It's enough for several days and if you want, you can spend your DVC points at the great hotels here. It's also the closest to New York so the long haul flight will be easier. In general, flights from Tokyo to the US have the best planes and flights from Shanghai to the US have the worst flight experience of the three locations.
Given that you own DVC and frequent WDW, Hong Kong will not have that much that is completely unique even though it is closer to Singapore. I recommend it more for complete Disney park beginners who don't know if they want a full day at a park or those who want to check it off their bucket list.
Shanghai could be a second choice after Tokyo as they have some of the newer high tech rides but WDW already has Seven Dwarfs Mine Train and will be getting Tron. The indoor shows here are the most acrobatic of the three resorts while Tokyo's shows are a bit more focused on characters. If we were just comparing the design of the castle parks, Shanghai may beat Tokyo Disneyland for a frequent WDW visitor but Tokyo also has Disneysea which I believe is the best non-castle park in the world.
Of all the parks in the world, Shanghai is the worst in terms of line cutting, shoving and children on shoulders during shows blocking people behind them while Tokyo has the best guest behavior. As a city, Shanghai also has the worst airport and most pollution of the three. The one issue with Tokyo is that it is very popular so wait times can be very high at times. Frequent WDW visitors may get frustrated at the patience that Japanese guests have. Wait times in Shanghai can also be high at times but at least you can buy premier access to skip the line while at Tokyo, vacation packages only give a few passes.
Of the three resorts, Shanghai is the only one I have never gotten an Annual Pass to.