The best park to visit today is Epcot. You should also be ok to visit Animal Kingdom as we expect average crowd levels there. You should probably try to avoid Magic Kingdom or Hollywood Studios or as we're expecting a fair few people to visit there. We highly recommend avoiding Typhoon Lagoon or Blizzard Beach or as we predict that it will be very busy.
There aren't any morning Extra Magic Hours planned at any park today.There aren't any evening Extra Magic Hours planned at any park today.
If you don't plan on watching evening fireworks or other events during the day, try and visit the most popular and busy attractions when said events are on. Since a large number of the parks visitors will be at the event, you should find the rides are fairly quiet.