7am or 8am EMH always seemed way to early for us (needed to get up as early as 6am!), so we would tend to avoid the EMH but always hit RD at a 9am park.
It really depends on how many days you are at WDW and have the interest and flexibility to select your specific park day(s) and whether your party members are ready to get going early or not.
I could never relate to those visiting WDW and saying that since they were on vacation there is no way they would get up and would rather sleep-in. For us even the kids understood the value of getting to RD to avoid long lines later in day, and besides with the excitement of a WDW trip we were always up early each day!
Our last five day trip we hit RD each day and were among the last to walk out of the park when it closed most days, granted park hours were typically 9am-10pm as it was off season, but we certainly maximized our time in the park most days (did take mid day pool breaks back at the resort a few times)