This year will be our third in WDW for the 4th. Here's our take. We went to MGM and saw their fireworks which I thought were disappointing. There were relatively short and set to rock and roll music with America as the theme (Born in the USA and such). The crowds were moderate for MGM's fireworks which were at 9:00 on the 4th. We then hustled over to Epcot for their fireworks which were spectacular. We stood on the bridge between France and GB. They did a full Illuminations show and then another 10 minutes of fireworks set to classical American songs (Stars and Stripes Forever and the like). We haven't seen MK's fireworks, but have heard that they are not as good as Epcot's. Last year, the noise and vibration from Epcot's fireworks set off car alarms in the Epcot and BC parking lots. Epcot also shows famous American landmarks projected on spaceship earth after the show (they didn't last year, though, due to rain). Epcot was crowded (the exit line out of the front gate from where we were standing started in Canada. We left Epcot and headed to the MK thinking we'd ride some rides, but saw the crowd and thought otherwise. The line for the T&T monorail was 3 hours long. We made our way into the park, and it was so crowded, we immediately left.
This year I think we'll try MK on the 3rd and Epcot on the 4th.