if you don't have hoppers or aren't staying on Disney property, avoid parks with them entirely.
The morning ones are good if you go and then go back to your hotel for napsie, then hop to another place. But keep in mind, they do fill the park up. On normal days by 11am, prime touring time is over. On EMH, days, that occurs at about 10-10:30.
The evening ones are better the later they are. But the problem is, the later they are, the less likely YOU are to want to get up the next day and get to that next park during prime touring time in the morning.
One note. If they suddenly add an emh while you are down there, regardless of park, avoid it. It means Disney thinks the park is going to be full for whatever reason. Obviously you cannot avoid it if during the week you're down there, they add one for MK every day. OOPs. I'd hate to be staying offsite THAT week.
Two note. NEVER, go to a morning emh park at regular opening time (Missing the emh in effect)