It’s fascinating to see the thoughts here, while I totally get the “I’m on vacation I want to sleep in” thoughts, I would counter with what goes through my mind, I’m paying a lot of money to be at WDW, I should plan my day to take advantage of it. I always rope drop and close. That said I park hop, have a table service meal everyday and usually take an afternoon break (and sometimes a nap.) The parks are at their most unpleasant in the early afternoon, they are so much nicer in the mornings and evenings.
It depends a little on the time of year- weather.
For those who only visit specific times of year:
summer: afternoon often around 90F, thunderstorms and heavy afternoon downpours are common, but often just a short burst. It may last 15 min, it might last a few hours, it rarely rains all day. Before the storm humidity is very high, August now = Halloween, Epcot = F&W
spring: spring break crowds, fabulous weather. Spring traditionally = extended park hours, Epcot = Flower fest, high prices!
winter: parks can be quite chilly in the AM/PM, water rides not as appealing and they often close for a month, only 1 water park, short park hours except holiday weeks, Epcot now has Artfest
fall: hurricane season, still hot in early fall, can be chilly late fall, and a bit unpredictable.
holiday weeks: high crowds, high prices, but often lots of soft attractions (like characters, special events), extra parades, decoration, and extra park hours.
The more temperate months tend to = cool am/pm and warm afternoons, so touring = carrying/shedding layers or maybe going to room for long pants, or maybe wearing long pants/jackets all day.
Weather-wise, in winter the AM/PM hours are less appealing unless you like 50's + windy.
In summer though, it is the reverse. Afternoons = storms and peak heat, so the earlier AM and later PM hours tend to be more appealing (weather-wise).
Just about all times of year, peak crowds tend to occur from about 11am - 5pm.
During slower times of the year, I find it is harder to take an afternoon break because the parks tend close so early. That's actually a plus of holiday weeks, more park hours. There's a major trade-off for certain, but the peripheral hours still tend to be fairly uncrowded, though not always.